I tested with Pinta-1.7 latest build 1.7+r1134-202008032046~ubuntu18.04.1 and Pinta only checks file extension.
This report should be marked as Wishlist, because it is actually not really a bug, but feature request.
If on Linux you can use simple command on terminal to rename files from *.jpe to *.jpg: rename 's/.jpe/.jpg/' *.jpe
I tested with Pinta-1.7 latest build 1.7+r1134- 202008032046~ ubuntu18. 04.1 and Pinta only checks file extension.
This report should be marked as Wishlist, because it is actually not really a bug, but feature request.
If on Linux you can use simple command on terminal to rename files from *.jpe to *.jpg:
rename 's/.jpe/.jpg/' *.jpe