Tvheadend

EDIT: I figured out that I have to add the UIDs with the corresponding channels to the srp-index file myself. Apparently I'm the first from my cable provider to use this.¶

I got a bit further. The first part "1_0_1_" and the last part "_0_0_0" are ignored anyway. I don't know what that remaining "unique" name is made of but for my cable provider it is not consistent with the default values.
My work around is as follows:
I run 1-build-servicelist.sh and select "2) Service Name" to get the file build-output/servicelist-tvheadend-servermode-snp, which is a list from tvheadend with both the unique identifiers and the escaped channel name. I then run a script I made myself which reads build-source/srp-index and tries to match as many escaped channel names as possible from there with the ones listed in build-output/servicelist-tvheadend-servermode-snp.
The matches are printed with the tvheadend unique identifiers and escaped channel names to stdout in the format of the srp-index file, so I can write it to my new srp-index file.
In the end I only have to manually look up those channels in the original srp-index file where the channel name could not be matched automatically. It's a one time effort, since once I've got my custom srp-index file the 2-build-picons.sh script will create images with the correct file names. I have to run 1-build-servicelist.sh with "1) Service Reference" selected first though because although "2) Service Name" creates basically the same file and one could use the output from that option for both build runs (if the channel name matches you know the unique id, because it's simply the one for this channel name), the build script wants the other output file.

Not the most comfortable solution though. And is there any documentation regarding the picons stuff? I just looked at the scripts and figured it out myself.

Not sure whether that is still helpful for you, but maybe for others as I went through a very similar exercise very recently.

I tried to build the picons from the same github repository you are using in a Virtual Machine via the tvheadend.serverconf method, i.e. by querying my TVH server. The command "./1-build-servicelist.sh" created empty servicelists all the time until I started analysing the script and realizing that it requires certain TVH settings to be present, i.e. under Configuration -> Channel / EPG -> Channels in the column "User Icon" you need "picon://1_[...]" entries. If that is the case for you, don't worry and you should be fine. But if not, the build-servicelist script will terminate. For me, fixing that required...
(1) Creating "some" picon path under Configuration -> General -> Base
(2) Disabling the image cache and cleaning the image (icon) cache
(3) Going to Configuration -> Channel / EPG -> Channels, marking all entries, clicking resetting icons and "save" -> This repopulates the "User Icon" entries with the right structure (see above).

Only after I did that the picons buildscript created the right servicelist. Once that is working, you are pretty much done though as the TVH backend will deliver the "right" picon paths "by definition" and the picon build will match the right icons to them...

There are certainly different ways to make it work, but that worked for me...

Thanks for the reply. No, for me everything was working except that the picon channel logo URIs did not match any existing entries in the srp-index file. I've added all the unencrypted channels from my cable network and issued a pull request on git. Other people with my network shouldn't have to configure anything in that case once it's in the main branch.