Hi there!
The GOG version of polish translation is a bit bugged. The translation you are using was known to be broken for years. It was patched by polish community before, because it does not contain changes from the latest SoD patch. The creature stats in crtraits.txt needs to be fixed, because it produces crashes in multiplayer:

- Cerberi:
damage 2-5 -> 2-7

- Lizardman:
damage 1-3 -> 2-3
Health 12 -> 14
Growth 8 -> 9

- Reptilioni:
atack 5 -> 6
defence 7 -> 8
damage 2-3 -> 2-5
health 12 -> 15
Growth 8 -> 9

- Serpent flies
atack 6 -> 7
defence 8 -> 9

- Dragon flies:
atack 6 -> 8
defence 8 -> 10

- Archangels:
cost 5000 gold -> 5000 gold, 3 gems

There are also two fixes for CrBanks.txt:
- In a "Griffins Conservatory" you can fight with 50 griffins for 1 angel, 100 griffins for 2 angels, 150 grffins for 3 angels, 200 griffins for 4 angels
- Naga bank now gives gems instead of sulfur

And the last fix is for editor.txt:
- Added "Właściwości" in line 696
- Changed "Gracz &%d" instead of "Gracz &%s" in line 729 - no more crashes, when editing hero properties in a: "map properties"->"Heroes"->"properties"

I was trying to insert link to fixed files on google disc, but it refuses to post my message. However, if someone is interested in this fix, please contact me.

Hope it will help!