Download, unzip and copy to your Gimp 2.10 plug-ins folder.

The filter can be located via:

Filters>>Custom Fonts>>Using Tools>>Custom Font Paragrapher v2.5b Tabbed...

This update adds another item to the alternative character options on Tab 1 of the filter dialog.



The option can be used with single case custom fonts that have a set of alternative characters.

The examples below show a set of lower-case characters with alternative characters in a broader weight...

Without the option:



With the option:



The next examples show an uppercase custom font that use both colour and shape alternatives.

Without the option set:



And with the option:

Thanks Skinnyhouse for the update.