as you can see i have made new savefiles as backups and also for each update. i also made sure to have my park completely empty from guests for each update, hotfixed excluded. and im not sure what you mean by convert, if you mean saving stuff as blueprints and moving over to a new blank park, thats just not possible at all. over 400k pieces.What I am a bit of afraid of is that these bugs arent fixable or very hard fixable, more or less imprinted on the save files as many bugs are very specific and not reproducable, for example your guest bug, i cant close one specific park or specific speakers not muted on the start the game. I dont know frontiers coding or anything, but i feel compared to other games, it can't be good to run one save file through numerous of patches as many other games (paradox games for example) make those older saves incompatible.
I know this is crazy, but have you considered to convert your park to a new file? i guess this is still to much objects even with the new limits?
and tbh i bought a product which i expect to work. nobody ever told us to wait out for the updates cause they might break our saves. its a full release game, these kind of things only happen to beta/ealy access games or games with huge complex updates. frontier didnt do anything huge or complex in their 6 updates, except for maybe the flumes.
if updates realy break the saves then there surely isnt any point in playing the game untill its reached the end of its lifecycle no? mind you we didnt have these issues with planet zoo nor planet coaster 1 so why should this one be any different?
either way, i hope one day we see these issues fixed and hope they realy are not related to what you mentioned. that would honestly make me outright quit planet games forever