I'm the author of the following plugin.

https://umod.org/plugins/spawn-modular-car

But I don't have the ability to tag the threads in the plugin's support forum.

https://umod.org/community/spawn-modular-car

Can this be fixed? I expect to have this ability because it works for another plugin I authored.

There's an open issue for it (not affecting only your one plugin), Calytic has to take a look at it when he is able.