RTF is a global modification that replaces all towns in the game.

No, I'm not saying they should be weak; they can be very strong while still having a normal growth rate for high-level mages. They will have less damage but more spells and mana, which is perfectly normal for scholar mages who don't have divine support.
A similar creature could be the NCF troglodyte, which has 96 hit points, 6-10 damage, 10 defense, 7 attack, and 7 skills, but its speed and initiative are lacking (4), and its growth rate is 2, level 3.
Mages usually have a growth rate of 3; chimera mages can have the same growth rate, with 50 hit points, etc.