Over on Mastodon it was suggested that "leuchtmarker" might a compromise. Still a valid German translation for highlighter (pen), but perhaps less weird and more pronounceable. What do you think? :-)

I do have to reveal: @nottinauta.bsky.social must be credited for this. I would never have never known what a Cartosemiotician is without her :-)

Thanks! You had the best excuse though :-)