I went to the sun school trainer to get enchanted cards. I just decided to train as much as i could. Did i need to get keen eyes and the accuracy enchants before i got monstrous or gargantuan? Or could I have skipped the accuracy cards. I know it's too late to cry over spilled milk but i at least wanna know if i wasted my training points or not.
You didn't need the keen/pierce enchantments in order to train the gargantuan series.
So yes, it was a mistake, but not the worst one you could make.
Along with accuracy, those enchantments also boost your ability to pierce through defenses. You may find those pierce enchantments are extremely useful during battles with enemies that love to spam shields, or who have high resist. Pack them when fighting against Ice or your own school.
You don't need to train keen eyes and all to get monstrous and gargantuan and all.. You wasted your points but sometimes they have free training point buyback for members so maybe one of those will happen again. But it's not too much of a big deal, you'll get more training points as long as you do Zeke's quests and that one Marleybone guy in Celestia base camp, and just leveling up in general.
The only prerequisites for Gargantuan are the previous damage enchants, e.g. Monstrous, Giant, Strong, etc. Getting the accuracy enchants is not necessary.
Even though you 'wasted' the training points, I wouldn't buy them back until you know that you can't get a spell that you want, e.g. other astral spells. I wasted my points on some polymorphs and I was still able to get everything I needed with a couple points left over.