honestly with the amount of spells and skills in this game it's weird that they didn't allow to stretch the skill bar in order to make it longer and have more than 10 abilities to choose from. or the other option, make it look like an MMORPG and have the bars of abilities stacks on each other (4 bars at once on top of each other)

I'm using Epic encounters mod, and the only way to survive so far is to actually use everything that I have. this means I also have a mage that has 2 spell schools and he has lots of spells. I need to be able to see more skills at once instead of switching the bars every turn just to see how many turns are left on a spell on cd or what spells are ready to cast again.

is there a mod or something I can use?

Unfortunately, the UI was not designed to be moddable.

are you saying the engine is the problem here? there is no way to actually add anything to allow something similar (like an additional bar)

AFAIK there is no way to add anything like this in a mod.