After the Intro of Disciples 1, I get the Error: DB Unit: Unit name "too long.
I get the Error only on my Netbook. On my desktop computer it works well.

Change the language to english. Then it works again.

When setting it to French it literally gives the same error but actually showing a unit name; "Chasseur de sorcières". This means the French data is indeed in there. So why doesn't it work? The error is obviously nonsense if it gives the same thing about a full name and about an empty one.

Looks like MULTI support dropped for game engine during developing. Text localisation still can be ALMOST fomplete translated in same MULTI files.
Back in '99 there is canadian french release, although probably that be only manuel/q.ref.card.

Game still can be almost multi. And sill English release never come wih Deu and Fra. There is only few strings there.
You need lurk for frnch version. Verok author of DisciplesGL also mak warez repack with most localisations of all games. Unfortunatly he miss documentation amd few maps for some lang version.
Try to google it with(!) "" symbols "disciples_setup". There is only fsw french strings in En version.

Russian version (second official dubbing) have strange issue with Tleaders file. Its correct but game Editor and only Editor closed with similar error.

Huh, so it's a cut feature. I see. Thanks for the info. Odd that they left it in the config file...

Kinda normal. Config editor have no language chose, ini file is ini file. Tefhnically they made engine to be multi. Dbf files are incomplete for Fre and Deu string.

Few dbf files required for text (T....dbf and Sinfo.dbf which one are main campaign maps file and so have also localisation text there) have 3 fielda for each lang, few didnt. It is still possible to make multi language pack (also with non fr/deu lang) and change language by ini file.
In that case it will work. Few string remain English. And no VO ofc.

Also maps possible to be translated using additional dbf files (also can be multi). Some localisations come with it remain .sga files on eng (for their compatibility online i guess).

Official localisations (known for POL, RUS, CH, FRA, DEU and unknown state of Canarian release) use English sections of dbf tables. Drop feature only for few string unavailability in localisation sections. So its not like also cut feature Windowed mode. It possible to use this one ini file language= argument. Not full trabslate but game will start.

Upd. And some text come as images and stored in ff/dbi files of Interf folder. Disciples 2 do not use graphics based text except splash screens/video for game titles in credits or first loading screen.

Verok say he found also Chinese files (i found repacked warez version of Disfiples 2 1.41 pre-GR ripped with no video/audio) but both Dis1/Dis2 use custom exe and modified files. He didnt put it to his repacks for not increasing its size to much.
As i say above for else localisations Veok repack can be used as language pack installer.
ESP version looks like only un-official (with hardcode subs into video files since in Disciples 1 there is no briefing texts - only short overviews of map file) and its also not present in his repack.
If you cant find FRA files i can put here magnet hash code. Or try lurk for it on Internet Archive for you. There is one disc image in Redump-PC set's and maybe another one as separate release on Archive org.