I've found that every single one of his lightning abilities are very, very loud when used compared to any single other skill of any other hero. Is this perhaps a bug?

nope, simply an oversight.
I tried to fix it a while ago but in my infinite wisdom I had deleted the soundfiles.
I'll try my hand at fixing it again, FMOD can get a bit finicky but I should be able to rebuild the soundbank from scratch.

when he uses "nimble defender" his riposte says it lasts for 1 round but will always fade next turn,

im unsure if its only when a enemy goes next, or if it anyone.

it's supposed to last 2 rounds, must have typed in a wrong number somewhere.
I'll go fix it right away, thanks for the warning

Had a bug where the game crashed whenever I opened the trinket box... is this fixed with the crimson court trinkets mod you made or no?