Even though the game is gonna get unplayable on joiplay soon, I'm gonna post this for anyone encountering the same issues I did.
Joiplay installation guide and common issues:
Installation:
1. Get the latest joiplay and rpgmaker plugin(some people use older versions and say it works better, but it works perfectly fine for me on latest.)
2. Turn off ALL settings for rpgmaker except graphical ones(such as linear interpolation), ruby and debug(this is probably the most important step, and really, this helps with most problems for most games). Especially don't forget to turn off cheats, they don't exist so the game wont load.
3. Use something like ZArchiver with japanese encoding(settings>compression>default character encoding>CP932 - Japanese Shift_DIS) and unpack the game into the directory of your choice.
4. Add the game into your joiplay library by selecting the .exe file in the directory you unpacked it into, and download rpgmaker VX Ace rtp when it asks you to. Joiplay will guide you through the steps, you just need to press a few buttons and then point joiplay towards the rtp archive which is probably in your downloads folder.
5. Try running the game, by now it should run, but when you start the game you will only see moving fog without seeing any tiles. If and when that happens, go back into joiplay and in the GAME settings(long press on the game), turn "enable postload scripts" on. If the game DOESN'T start, do the same, and it should. We turn it on after the game doesnt work for the first time for a chance it will work without it, since the less options you have on, the better.
After that the game should start and work fine, but you have to be careful to not turn any other settings on if you install other games, especially path cache. It fucks up the game for good from what i found, and the only way to fix it is to do a full reinstall from step one, including reinstalling the RTP. A sign of that happening is your game starting into the main menu, but then not loading the save file or unable to start a new game, saying it couldn't find files like "other3" or "vehicle", or some other similar common file names. Those files do not exist and should not exist in the game, but its looking for them because of some magic fuckery(probably some persistent cache file being saved somewhere even after you turn the settings off)
To reinstall the RTP you need to go into settings, scroll down and press "Clear runtime packages", then point it towards the rtp archive again.
Another common issue is when you'll try running the game, but it wont load because of a bitmap script error, something like "ENOENT... ...31 bytes left". This happens for one of two reasons, you either used the wrong encoding when unpacking the game, then just do it again with the correct one, or joiplay for some reason didn't run the required scripts. If you did use the correct encoding, "Enable postload scripts" should fix it if the problem arises, but the very first time i installed it, i had that issue, and i dont quite remember what exactly caused it, so if the problem doesn't go away, the only thing you can do is restart from step 1 and pray it works. I know, not a great solution, but it worked for me first try.
If anyone has any other info on those issues, or any other ones, feel free to tell me and I'll add it into the post. Hope this helps any lost souls like mine, and saves you some time!