thep wrote

Thanks for the info.

I wonder how to contact the maintainer. Would they see this thread of mine, or should I contact them directly?

Regarding my second question (translation testing), I have tried building LibreCAD from Git with librecad_th.ts added to TRANSLATIONS variable in librecad/src/src.pro, but the translation didn't show up. Then I finally found that I mistakenly used the traditional method of LC_MESSAGES setting. The effective way is to set "GUI Language" in Options > Application Preferences dialog. So, now I can test my translation on the APT-installed version without rebuilding. Thanks for your help.