Your provided information is lackluster, we do not know which class you play, which is essential to answering this question, as it is depending to it.
Basically, every Class has a different value for its "crit cap" because skills work differently with Crit. If you want a "real" crit cap then the value would be at like +1200, only then would any skill start to crit safely
Edit: im stupid, i should have read the thread you posted it inside :C
Sorc plays with around +280 crit factor, that being said you end up with something 405 in *Total* , 50 + 280 + 75 from glyphs
This is not really a Crit cap, its just a ideal sweetspot to be at. If you overshoot it by like 20-30 Crit factor is fine, undershooting is not recommended.
your aim regarding Crystals and accs should be to use as many Power accs baseline but still reach your desired crit factor