This suggestion is probably too late in your case, but,

I used my scraper while the epoxy was still green, running it first along the deck panel and then along the sheer panel (or vice versa), which did a positively spiffy job of taking off the excess epoxy and leaving a little sharp-peaked seam. A light third pass with the scraper perpendicular to the joint might take off the sharp peak, but I think I took a sander to it (carefully) after it had cured.

: I have recently glued the hull and sheer seams of my Artic Tern 14 and I am
: in the process of rounding them. How particular do I need to be about
: feathering in the excess epoxy into the wood panels?