Thanks for your report and for your efforts to nail the problem. Unfortunately the solution you propose would not be a proper fix. "JP" is not a "lang" thing, the purpose is to match part of the family name.
Nevertheless, there seems to be something with that configuration file. The similar bug #1787215 was reported a few months ago.
Attached please find an idea of a modified file. Would be great if you could confirm that it addresses your issue.
And @Mitsuya, can you please confirm that the modified file works as the current one when rendering Japanese.
Thanks for your report and for your efforts to nail the problem. Unfortunately the solution you propose would not be a proper fix. "JP" is not a "lang" thing, the purpose is to match part of the family name.
Nevertheless, there seems to be something with that configuration file. The similar bug #1787215 was reported a few months ago.
Attached please find an idea of a modified file. Would be great if you could confirm that it addresses your issue.
And @Mitsuya, can you please confirm that the modified file works as the current one when rendering Japanese.