The rows of rivets appear to taper but does that necessarily mean the underlying structure had to taper, given a poorly aligned rivet job?
Applied an over lay showing one possible fit for 1" parallel stringers on 4" or 4.25" centers.
No, it does not necessarily mean the underlying structure had to taper, it is merely implied. Had 2-2-V-1 simply been a scab laid over damaged skin, any pattern is possible - including to have even possibly ignored stiffeners and just picked-up skin adjacent to stiffeners (which would largely assume the original skin was left attached in original fashion to the stiffeners).
Or we could be seeing a deviation where damaged stringers were straightened and new skin reattached. Problem is, 3/4" (original L10 spacing more on order of 3.5" I believe) is significant. It is not, however, impossible - and your illustration makes a good point of this.
ADDED:
Further to this point, what IS the actual width - outside and inside of flanges - of the stiffeners in the L10? Reasoning: the keel line makes sense, as does the first line of rivets (3.5" offset, as per L10 original), but the others are fairly uniformly displaced 3/4" - implying a sister member laid in for the next three stiffeners. Consider that the area we are talking about was subject to 'straighten or replace' on the work description, so a fair question is whether straightening might have happened, with some additional bracing added to keep contours and stiffeness in good order afterward. This is far from unheard of in repair world and kind of a battleship tough approach.
It would have surely beat having to rip out a full length of stringer just because a couple of bays were bent up, and faster and perhaps stronger than splicing in a short section as well (more original stiffness retained) - straighten them as best one can, then lay in a sister member next to the original.
Conjecture, of course - but looking at the picture, far from out of the question.
As an aside, when we look at the B-17 we may find more constraint as to row spacing - the corrugated stuff underneath is monolithic as to ridge spacing so I wouldn't expect as much potential for variation like we see here. But seeing is better proof, so we shall see on that and other types.