Is somewhere any documentation of this file?
I created simple tool to create .png files for all current emojis (using unicode.org data), but I don’t know how to make correct ‘theme’ file. And I don’t know if such tool can be published as pidgin tool (for legal reasons, I’m not lawyer and I don’t understand Unicode license terms 
)
I thought we had a page somewhere but I’m not finding it at the moment. There are a bunch of existing 3rd party themes at ThirdPartySmileyThemes – Pidgin which might be helpful examples. If you’re still having issues let me know and I’ll try to throw something together to explain how it works.
I checked existing files, but still doesn’t understand its structure. On first look, I think that Pidgin is looking for file with filename = codepoint. But seems like it is not true.
Section [default] in ‘theme’ file has entries, with filenames and one or two additional columns… I could “extract” format of theme file from pidgin source code, but I don’t know where source code exist
Oh you want to go to code points? Yeah that’s no doable the format is only for using files. That said there are a few themes that do this already like GitHub - stv0g/unicode-emoji: Apple, Android and Standard (Symbola) Unicode Emojis for Pidgin
But these themes are outdated, i.e. not current Unicode. Too frequent squares instead of emojis.
My tool created much more PNG files (1938 png files, not ~850 as in stv0g theme). I just created PNG for each entry in Emoji Proposals, v15.0
Sorry for the late reply, I got side tracked and then lost track of this draft.
You’ll need to use the cldr names to make pidgin2 handle them as the theme format does not handle unicode code points. The best way to handle the unicode code points in the program is to have a font that has them.