NEVER go full int.
1- Transpose sucks, and you shoudn’t base your build on transpose, because it sucks.
2- Anything you equiped, like a % buff on int, or a buff % on con, or a + int, + con, will still giving to you the same stats when you transpose your stats.
3- Thauma is a fake tanker, with swell right arm you can mitigate a lot of damage and if you go full int you will need to transpose everytime you need to tank, and that’s 9/10 times when using FF because we have closed range skills.
4- On a party, more than often one of the party buffs will remove your transpose.
Anyway, it’s a great build, hard on lvling until you get FF but you will enjoy. I wouldn’t recommend getting as your first character, but if you want, why not. Also, answering your question, FF is not very good for world bosses.