No and Yes
If you aim for control, support, buffs etc. it is not to low. If you aim for doing most of the damage with your spells, I will say that your int is too low. Spells like Fire Rain, Death Star, Fireball, Armageddon, Ice Snake, Geyser, etc. are very good with a high int. Death Star can easily reach 10k or more with a high int. On the other hand, remember that the burning and poisoning post effect damage is still very effective even with a medium int.
There are two things you can do to boost your int. The first is picking all the skills and achieving the medals that gives int. The second is pure luck... Here is how I ended up at int=58:
What you can do:
Play Mage: It starts with Int = 3
Medal: Illiteracy Exterminator +3
Magic Skill: Linguistics +6
Magic Skill: Thesis +6
Mind Skill: Scouting +3
Mind Skill: Learning +3
Elenhel as companion +4
A total of 28
The rest is pure luck:
2 x Dress of the Magess: 2 x +4
Engineer's Badge: +2 (I do not use droids - I only use it to get +2 Int)
Snake Ring of Wisdom: +5
Band of Concentration: +1
Boots of the Mystic: +2
Diploma in Anti-Magic: +2
Shaman's Skull: +3
Used Ring of Mind, class 2: +3
Shrines 4 x +1 Int
A total of 30
That is 58 in total. I am 2/3 through the game and there is still room to improve my Int. I know that the Usurer's Ring is in Reha for instance. That will push my Int to 63. I can replace the Portrait of the Knight that I still use. Of course, this one-sided focus on int hurts my other two stats. My Attack is 4 and my Defense is 13. The only Attack/Defense items I use are: Mithril Shield (Def +8 ), Inquisitor's Blade (Att +3 and 20% Leadership reduction for Paladins and Inquisitors that I use), and the Diploma in Anti-Magic that has a +2 Defense (It is mainly used because of +2 Int and +25% Magic Resistance).