The performance will be affected. Whether or not adversely will depend on how you fly the plane.
Having done that error in installation in the past, I've found the cure is to take the part that is accessible and modify it to fit properly by trimming and shimming.
Your filling the gap with epoxy kinda prevents this from occuring now, though.
Next one, pay attention!

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Along this line, filling the gap with wood and epoxy is preferrable to using epoxy only.