the existing plugin pack can already do it and it is fully compatible with existing saves.
Proof:
View attachment 2201883
the items with a /9,999 after them use "Max Items" value. (ex: antidote)
While the items without it use "Default Max". (ex: wheat)
for the dev it is even easier to change. he just needs to go to YEP_CoreEngine and set the value he wants.
I have no plans to extend the max amount of items over their current limits. Yes, that could be done as you pointed out, but it's a design decision to have them where they are now. Originally I had plans to limit the inventory even further to make it more realistic (so that you could only carry 200 items in total) but I moved away from that idea because it would have been too tedious for the player.
As it is now there are no resources that don't respawn. So you can always get more and you can carry an amount of each that is enough for any demand. Also the amount of gold that drops isn't that high, it is pretty much required to sell goods so that you have enough money for all demands. So it's not as realistc as I would like it, but at the same time the MC isn't a walking lumbermill.
I'm aware that the balancing of that isn't perfect. I could probably spend a whole month just with balancing, but I don't have that much time or I wouldn't be working on new content anymore.
I had the idea to add a storage system when I did the MC's house upgrade. Problem with that was that it would require another save reset (adding the required plugin would break saves). This is something that might come in the future, but I'm not doing another save reset just for that. This would solve the issue you have while still not breaking my idea of a limited inventory.
So if you want to increase the cap for yourself, then that's your thing. You can do it as you did. But I'm not changing the current limits.