It has been said before, but it bears repeating:
When importing a raster image into Inkscape, the only manipulation you should do is locked aspect ratio scaling. Do not rotate the raster, your engrave will be ruined in weird ways.
Use your favorite raster editing program to do anything you want to that image prior to importing.
Rotate your vectors all you like. But do not mess with your rasters.
also import your rasters with a white background, don’t do it transparent. Ruin awaits. I’m told I’m incorrect here about transparency. But I’m serious about rotates.