I've been looking at the 'Why do some fonts in Gimp have a # at the end and become unusable (under windows 10, at least)' question.

After a lot of hacking about, FontForge shows me that, in my test OpenType font-set*, Gimp picks up the 'Preferred Family' string in TTF Names section of Font Information in FontForge or, if the 'Preferred Family' information is unavailable, it defaults to the PS names 'Family Name' setting in the same FontForge section.

Can anybody tell me why this is the way it is, please?

Inspecting the font in Windows' Font Preview option in Windows file explorer, the FontForge Element>Font Info...>PS Names>FontName seems to be in use; while the received wisdom seems to be 'it's all down to poor work on the part of the font creator', it occurs to me that picking up a font family rather than a font name is going to cause difficulties. It also occurs to me that the folk that develop Gimp, like Technical People everywhere, Had A Good Reason At The Time and that I'm walking in very late to the discussion, so, if anybody has some background on the subject, I'd be interested to hear it.

In passing, I've knocked together a quick FontForge script to alter (or delete) the 'Preferred Family' section in TTF Names, so I do have a workaround for my own system in place for the time being.

*My basic working set is a commercial, OpenType font family 'Farmhouse' because it just happened to be the one I saw first when I opened up the font list. I have, as yet, done no work on other fonts or font formats. I am NOT (yet - give me a few days) a FontForge expert, nor an expert in fonts, generally.