very nice work shown for those that have inserted modern, small batteries, into a period case .
the only thing i can suggest, would be to use marine heat shrink [with the glue inside that seals the tubing] at the crimped end connection to insure humidity and/or outgassing from wicking into the cable[s], causing corrosion to start at that point. an extra few seconds to add to the assembly, but as i have repaired a ton of wiring issues over the years, this may be worth considering on something you can't see without going to a lot of effort.