B4208:
Split A438 into 2 wps
Definite overlap!
B4208:
PeaRd -> PicRd_N
Not only is the road Peach Road, but PicRd_N is another point, so this would be a duplicate label. Was there something about these two points that wasn't rename one as the other?
B4232:
Replace eastern end point B4503 by wp at A449 south of the church. Confirmed by OSM, GM and GSV
GM has the segment you suggest (correctly) marked as B4219 - so actually it confirms what I have, not your change. I spent some time sorting that area out when drafting as signage is confusing. The one GSV sign (pointing to the main bit of B4232) is not only old, but directly contradicts the data the authority that erected it has on what road is which - I'm going to suggest they put the wrong road in brackets, which would be a fairly simple mistake for a signmaker to make.
B4289old:
Merge into main route? It's just a short concurrency with A4289
Any other A road, sure. However it's a single numbered route (forming a box around Swindon) that changes what system it's part of. cf things like Ax(M) breaking up Ax routes, but with more certainty as an argument can be made that they are part of the A road, whereas the A4289 is explicitly not B4289.