Hopefully fixed for the next release, and hopefully it is a retroactive fix as well.
All implants that affect breast size (Ballistic Breast Liners, Busty Bulwark, Medical Milkers, MedImplants) should now properly add to the size on install and removal. Only MedImplants affect all rows of breasts (and should work on newly-created breast rows while the implant is equipped), whereas the others seem to only affect the top-most row of breasts.
These changes should also make the "Implant-tastic" perk silicone conversion calculations work alongside it as well. If any of the values are misaligned, there should hopefully be a "Fix Size Mod" button that appears in the appearance menu to help correct any out-of-synced calculations. If there are still issues with the sizes or implant in the next release, just uninstall the implants, check if there is a "Fix Size Mod" and choose to fix it, then install a new implant to replace the old one--this should cover all the points of failure related to the bug.