Thanks Adam, we tested here before and were able to reproduce through the link you provided.  Here's what we get.  When we followed the use case above the font type is not being changed as should be the case for the whole line just for part of the line in WYSIWYG way because the second word is still wrapped by the old tag.  It wasn't overwritten when new font type was applied to the whole line.

 

 

<span style="font-size: 14pt; font-family: Times New Roman">hello <span style="font-family: Comic Sans MS">world</span></span>