This may have been reported already. I recently downloaded ADE version 3 and version 4. They seem to no longer support the xpgt template files.
The only reason I was using the xpgt file was to assign alternate font-formatting for the ADE readers. (such as my Gilded Age project
https://www.mobileread.com/forums/sho...d.php?t=235603 [shameless plug!], with lots of unicode fonts and RTL languages.)
So, by extrapolation, I would imagine that in several years, ADE-based readers using newer versions of ADE will no longer be able to use the xpgt templates. I guess it would have been too much to expect that when they killed support for the xpgt, they would simultaneously begin supporting the formatting ebook makers were using them for.
I'm depressed now...