What are infoLayer "Level" images and where to get them? See details from fieldGround.xml page.
You can generate infoLayer_ "Level" GRLE files by starting a new career and save it, FS22 will generate those lime/plow/roller/spray/stubble level GRLE's image files in the savegame directory.
You can then just copy them over to your terrain project GDM/GRLE/PNG aka data/ directory.
Note that infoLayer Level images work just fine as PNG image format, no errors or issues. Giants Test Runner for FS22 does complain about Level images not being GRLE though.