Tvheadend

I'm not sure you have a choice. Looking at this:

http://mavise.obs.coe.int/satellite?id=99

... suggests that that channel is in English Europe-wide but perhaps also targeting Vlaams, which would explain the default subtitles.

Specific channel here:

http://mavise.obs.coe.int/channel?id=4813

.. although there appear to be versions in Polish, Hungarian and Czech on the same mux if you're feeling truly international.

The SE version of the channel is on Cable and IPTV but not satellite:

http://mavise.obs.coe.int/channel?id=9290

Soooo.... it might be that there simply aren't any Swedish subtitles in this stream because there's a Swedish-language version available from elsewhere?

When you lock onto it, what does the logfile say about the PIDs in the stream, anything there?

Is there even a Swedish audio stream?

It doesn't look like there is from here - http://en.kingofsat.net/tp.php?tp=3418 - There could only be subtitles matching the audio.

3303 eng
4135 cze
4137 hun
4138 pol
4159 tur
4188 ned

The audio stream is English.
According to my provider CanalDigital (http://www.lyngsat.com/packages/Canal-Digital-Sverige.html) they have Swedish subtitles (not only for Cable & IPTV but also for satellite) ... just don't understand were they get it from ... pure magic.
I can live without Swedish subtitles - is there away to get English instead of Dutch ?

You can cycle through the subtitles using the Audio menu in Kodi to check what is broadcast.

And, if that doesn't work, you can still dig into the broadcast to see what is available. If I just grab a recent recording from my syslog, I get:

Mar 12 16:54:33 Romulus tvheadend[13902]: dvr:  #  type              lang  resolution  aspect ratio  sample rate  channels
Mar 12 16:54:33 Romulus tvheadend[13902]: dvr:  1  H264                    ?           ?
Mar 12 16:54:33 Romulus tvheadend[13902]: dvr:  2  AAC               eng                             ?            ?
Mar 12 16:54:33 Romulus tvheadend[13902]: dvr:  3  AAC               eng                             ?            ?
Mar 12 16:54:33 Romulus tvheadend[13902]: dvr:  4  DVBSUB            eng

... so you can see the audio and subtitle streams that are available. If it's not in the stream, you clearly can't select it no matter how many buttons you press.

Or you can play something back in VLC, and that easily lists the audio and other streams (Tools -> Codec information).

There are also numerous tools to analyse the TS file and list the elements of the stream if Kodi can't tell you for whatever reason. At least you'd know what you've got.

And finally... if things are there but simply coming out in the wrong order or otherwise creating a challenge at the Kodi end, you can always use the filters (Configuration -> Stream on the tvheadend web interface) to suppress the ones you don't want so that Kodi is selecting from a much smaller list and thus might select the right one if e.g. the language or default flags aren't working properly.

Failing that, move to Ghent :-)

Here is my syslog from a History HD recording.
It seems that swedish language is in the stream (dvr: 2) but dutch language is first in line (dvr: 1).
How can that be fixed so TVH takes swedish language first ?
I have in Configuration -> Stream on the tvheadend web interface enabled all 'htsp' & 'matroska' & 'pass' ... is that OK ?

Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: "History" on "History" recorder starting
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: subscription: 0043: "DVR: History" subscribing on "History", weight: 300, adapter: "STV090x:3", network: "Thor", mux: "12015H", provider: "Telenor", service: "HISTORY HD"
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: pass: unable to add stream 13 MPEG2AUDIO cze (PID 4135) - no space
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: pass: unable to add stream 14 MPEG2AUDIO hun (PID 4137) - no space
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: pass: unable to add stream 15 MPEG2AUDIO pol (PID 4138) - no space
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: pass: unable to add stream 16 MPEG2AUDIO tur (PID 4159) - no space
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: pass: unable to add stream 17 MPEG2AUDIO dut (PID 4188) - no space
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: pass: unable to add stream 25 DVBSUB gre (PID 6642) - no space
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: /home/hts/History.ts from adapter: "STV090x:3", network: "Thor", mux: "12015H", provider: "Telenor", service: "HISTORY HD"
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: # type lang resolution aspect ratio sample rate channels
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 1 DVBSUB dut
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 2 DVBSUB swe
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 3 DVBSUB dan
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 4 DVBSUB rum
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 5 DVBSUB srp
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 6 DVBSUB slv
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 7 DVBSUB hrv
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 8 DVBSUB nor
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 9 DVBSUB fin
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 10 DVBSUB bul
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 11 H264 1920x1080 ?
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 12 MPEG2AUDIO eng ? ?
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 13 MPEG2AUDIO cze ? ?
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 14 MPEG2AUDIO hun ? ?
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 15 MPEG2AUDIO pol ? ?
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 16 MPEG2AUDIO tur ? ?
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 17 MPEG2AUDIO dut ? ?
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 19 CA
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 20 CA
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 21 CA
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 22 CA
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 23 CA
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 24 CA
Mar 17 13:05:09 tv-server tvheadend⁷¹⁰: dvr: 25 DVBSUB gre
Mar 17 13:05:24 tv-server tvheadend⁷¹⁰: subscription: 0043: "DVR: History" unsubscribing from "History"
Mar 17 13:05:24 tv-server tvheadend⁷¹⁰: dvr: "History" on "History": End of program: Aborted by user

Isn't this where a Subtitle Stream Filter will be useful?

I created following subtitle stream that I enabled:

Stream Type: DVBSUB
Language: Swedish
Service: Thor/12015H/HISTORY HD
Stream index: 2
PID: 6512
Action: USE

Not sure how to get the 'Stream index' & PID - I looked at 'Configuration/DVB Input/Servies' and clicked 'I' for information for that channel and took PID & Index from there.
Restarted both TVH & Kodi but still Dutch ...

I've never used any Stream filters myself but does "Exclusive" work?

Or maybe "Ignore" with it set to dutch?

(Someone with an idea of how to use them might be better to answer!!)