Hopefully you’ll be measuring the Specific Gravity, pH should be 5-7 but not as important for seeing cell health as the SG. Just remember PPE, acid will corrode your skin and clothes!
If you can’t find the original data sheets for your cells, have a search for Hoppekke, Bater, Zvei etc 2v lead acid data sheets and battery care instructions.
TBH you can probably nurse your cells for now with a decent full day (12h) charge with 4h+ absorption and then 1-2h equalise charge, start the genny before the sun gets going on a day you know will have some sun, then let solar finish off, but you probably will need a good equalise charge if they haven’t had one in a while, (once a month or so) but I’d be looking to save up and build some LFP batteries or buy a DIY cell kit from Alibaba if you can’t afford off the shelf rack batteries etc. Look on diysolar forum for research or just go to Fogstar in the UK for their Seplos etc kits, not perfect but a good and cost effective way of going LFP and closed loop communications with Victron.