I've tested this twice before asking.
If I'm importing an xml into a pdf and there is ONE single character that is not available in the original font style, so I chose another font style for that ONE character, is it then normal that the font in the original is replaced by the 'new' font in the WHOLE document.
I don't remember Infix behaving like this before. I seem to remember that it would replace the font just in the ONE character
Infix has always worked in this way. I checked Infix 6.20 and it behaved the same.