Hi there!
I think that the abilities of engineers and beholders are not overpowered. Beholders are supposed to put lvl1 units to sleep 100% of the time, except undead and some others which can get nasty. The chance is 100%-50%-25%-10% for lvl1-lvl4 units respectively.
To Sir Lancelot - try playing on impossible, I always do
About the translation of my mod, I think I'll do it on my next playthrough, but I guess that will be in the end of march.