So after having to deal with a couple situations where a model I made and a model I got for pngtuberplus were created at overly large resolutions, I decided to do something productive about it rather than spend the tedious amount of time necessary to manually adjust all of the offsets/positions/amplitudes and downsample all the images. (I've had to do this before and it's not fun if say you've got models with dozens of sprites in them!)
Since the files are all plaintext jsons, from a technical standpoint this wasn't overly difficult.
Anyway, I've put the fruits of my labors up on Github for if anybody else feels the need to resize a pngtuber model. Works with the latest version of the software (1.4.5). Hopefully this saves one or two people some time.
https://github.com/GeneralTekno/PNGTuberPlusResizer