Here's a decompressed single level spliced into an original Doom dump with the .jag file extension flashed to a Skunkboard and running on real hardware. No offset on the status bar at the bottom.
Quick ref:
Level: single
Compression: none
device: Jaguar/Skunk
dump: original .jag

Here's the same file running in Project Tempest. Has a slight screen offset (?) but st.bar stays in place (as far as I can tell bc the distance between the edge and the 50 of ammo is still close)
Level: single
Compression: none
device: PT
dump: original .jag

Here's a shot of the same decompressed level spliced into a ROM, made from JiFFI, and using a custom build from the source code. Bad offset:
Level: single
Compression: none
device: PT
dump: custom build from source code with mods, and ROM made with JiFFI

Looks like it's either the custom build from source code and/or the process of ROM creation using JiFFI. Will test these next..

Attaching the images in case photobucket is down... again.