Tvheadend

I have tvheadend in a container feeding streams and XMLTV to xTeve (also a container) which in turn feeds it to plex (which is also a container)

The above works just fine with a minor detail. For some channels I get missing EPG.... only time slot with a description that there is no info in English but only in Greek. Some other channels (which have the information only in Greek) work just fine!

After checking the xml data I found out that for the working channels there is only one title and one desc line per program. For those not working there are 2 for each.

Working:
<title>Program</title>
<desc>Description of program</desc>

Not Working:
<title lang="eng">Program</title>
<title lang="gre">Πρόγραμμα</title>
<desc lang="eng">No information in English.</desc>
<desc lang="gre">Περιγραφή προγράμματος</desc>

It seems like Plex (and Jellyfin which I also tested) want to always select the "eng" options... I guess cause they do not understand the language codes.

Is there any way for changing the language codes (if this is the cause) or reformat the xmltv output to the simpler but fully working format?