I sincerely hope that this will come across as constructive criticism.
I played a bit of ERP, and also a bit of HRP recently. I've never been a fan of HRP, or rather of the idea of such drastic change/improvement to the original art, but it (HRP) works really well with Polymer lighting and stuff.
Many textures in ERP on the other hand, look rather lacklustre to me in-game, and I have trouble convincing myself that these are an improvement over low-res originals.
At the same time, many HRP textures are actually fairly faithful to the original source material, and they look much better (IMO) even as these quick palettised mock-up 2x downscaled versions compared to their ERP counterparts (taken from the ERP first release at ModDB):
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On a side note, of the above, tile0237 looks particularly bad in-game, especially since it mangles the horizontal pattern at the bottom into a snake-like wavy thing.
Since ERP already makes use of some HRP assets where ESRGAN clearly fell short of expectations, perhaps you should expand this to as many good HRP textures that you can use?
It is my understanding that AI upscales had been originally thought to provide better accuracy and faithfulness to the source low-res textures. However, so far I'm being convinced of the opposite, namely that the work of human artist is truer to the original art even when the result is not a 1:1 match of all details in the source image.