I employ Probox hawaii fin system which has different inserts for 0 4 6 and 8 degrees of cant and ~1/2 inch fore or aft adjustment.
I find the 0 degree cant boxes make my board want to turn flatter and seems less happy on rail, where as more cant it holds higher in the wave face and is happier on rail and turns crisper, but is easier to overpower when really laying into a hard bottom turn, and more so when that bottom turn is not quite in the Trough but lower to mid face…
I predominately use the 6 and 8 degree inserts on my rail fins. The 4 and zeros in my rail fins never felt good to me, and I did not really try again, but it could have been the conditions.
Try your fins as is, get used to them, then borrow something different, or modify their bases to have some fin cant. If you find that when you put the board on rail it fights being on rail or just does not respond like you would prefer, then fin lack of fin cant could be part of the problem.
Handfoiling fins and achieving a nice foil is quite difficult, and foil has a huge effect of fin performance. When I take a contour gauge to some of my earliest fins, I wonder how I ever once thought them acceptable and that they worked well. The same contour gauges used on store bought fins will also reveal poor foils on many.
One can slap a flat plywood ‘fin’ in their board and keep the assend from sliding sideways through turns, and on good waves might even feel ‘just fine’. But a well foiled fin opens up a whole new playing field.
Dont be afraid to go thick either, a thick fin is much easier to hand foil accurately, and thick fins turn better.
Advanced beginner/ bad intermediate is not going to notice any added drag in straight line trim speed from a thick fin, but they will be able to feel more fluid response and stability through turns with a thicker fin.
So try your fins as is, but plan on making more, with better foils and with some cant after you borrow some to compare the feel.
I bring a fin key and sometimes another fin with me in my wetsuit to change in the lineup. I have changed fins, and moved fins for and aft, and switched the canted inserts in one session just to see the effect in the same general conditions.