No, I don't sail/race formula anymore, but I know that a few years back all the formula racers were
tipping the fin in the box a few degrees on an experimental basis, then as soon as they determined the
optimum angle, they added material in the appropriate spots on the fin root and refit the fin to the
box in the optimum orientation.
If your fin has zero rake on the trailing edge (many formula fins are designed this way so the flow over the foil is normal to the trailing edge) then you can use the trailing edge to measure the leading edge
Most top of the line formula fin designers have already done the research to optimize the leading edge angle, but perhaps not on all the different boards.
If Remi, Sean, and the Starboard Formula team suggest a particular fin for your HWR (do a search on
HWR and you should find quite a few fin recommendations) it might be good to get one and try it compared to the fin you are using and see if it solves any of your issues.
Sailing fast upwind on a formula board requires several very "non-intuitive" techniques.
Railing the board slightly to leeward to go upwind is very non-intuitive, but if you watch the worlds best
formula racers, they all do this to some degree.
Flatter is faster in slalom, but slalom does not require the extreme upwind/downwind sailing angles that are the norm in formula racing.
Hope this helps,