Well, this is in the beginner's forum, and for beginners, a slightly out-of-balance (Laterally) plane will not really be noticable.... BUT it does affect flying performance.

My advice fo an out of balance wing ... just put the plane together, get it flyable, and then go fly. Read up on how to flight trim a plane, especially getting the CG right, and the lateral balance.

A problem with model aiplanes is that the engine is normally set with an amount of right-thrust. Further, the plane pivots around the center of gravity, and this is not tecessarily in the middle of the fuselage. Balancing the plane laterally on the ground is not very useful.

So, read up on how a laterally unbalanced plane can be identified by uneven loops, and so on. An unbalanced plane may appear to be corrected by using aileron trim, but the reality is that the plane is now going to fly badly when inverted, and it will not track perfectly straight through loops.

So, lateral balance IS important, BUT, there is no accurate way to correct it without actually flying the plane.

gus