Thank you for your comment.
I already support character sprites on SRPGStudio maps, but do not have detailed documentation available. The image below shows a character sprite loaded from SRPGStudio for testing. 
To support SRPGStudio, you need to use the character.json editing tool at the URL below or edit character.json directly. The program itself is available in English. I found a bug in the program the other day, when I reload a file saved for SRPGStudio, the SRPGStudio check is disabled. This will be fixed in the next version. Please be aware of this.
https://pipoya.notion.site/CharaMEL-character-json-9c9cacb9feee458283770d6213bd0...
To edit character.json directly, change it as shown in the image below.
I am not yet in a position to fully support you, so I am sure I am not explaining myself well enough, but please try.