No, I do not want bold, I want thin, was just an example. Some fonts types do not have different versions of weight, they relay on css for it, that is the modern way to do it, if your not compiling it in. Volumio gui is on a webbrower, so need to compile in.
I am not an amateur, I work with web-programming. If I can get to know witch file to change, the risk the plugin broke is minimal.
(I surpose you wrote mainly to me, but did not clicked my message as response)