A 1/4 inch piece glued to the end of the spar(s) like in your picture is NOT going to make any difference as long as the piece feels solidly attached. CA or not.

There will be so little stress placed on those glue joints (by the time the other spar is added, the wingtips built, and the wing covered), that it will not be an issue. If you're still concerned, add a thin strip of balsa to each side of those joints as stiffeners.

I'd highly recommed continuing with your construction and chalking this one up to "lessons learned".
Dennis-