BTT button on the Touch Bar should send a letter in a specific font

I'm writing text in Medieval Latin. The BTT buttons I've created for the Touch Bar point to special letters, symbols and characters with ligatures and are only visible using a specific font (i.e., Junicode). Would it be possible to add the font type when the BTT button is pressed on the Touch Bar? The next letter pressed on the keyboard should use the default font (i.e., Times New Roman, etc).

Can't this button paste the letter, preselected from the special character list (⌘⌥space)?

I can paste the letter, but the font type isn't carried-over.