[01:46:22] [Render thread/WARN]: Skipped language file: ae2wtlib:lang/ru_ru.json (com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException: Expected ':' at line 2 column 30 path $.gui.ae2wtlib.creativetab)

Just add anything to "gui.ae2wtlib.creativetab"

(ae2wtlib 15.1.3 fabric)

Thanks for reporting, I will release a fix soon