Not sure I'd be that concerned.
1> Builder has a reputation. Not inclined to put something out that will deface itself into a disaster in short order, so assuming/assigning a fair degree of confidence on their part in releasing the instrument finished as it is, regardless the debate of sealed/unsealed.
2> I play my raw ebony fretless board quite vigorously with RW's, like yourself, they're just my preference. Sure enough. Witness lines! Gasp! Will those strings eventually grind my neck into oblivion, like a slow form of torture in the form of the world's dullest file? Doubts. Just realize, the dented areas are now compressed, and naturally reduce the tendency to gouge deeper, now that it's firmed up and at least at a microscopic depth, the density is increased. Unless you sand it smooth. Then, it is possible you'll slowly be contributing to it's demise, as it will re-compress the fresh new surface you've exposed by sanding away the offending indentations. Point being, obsessing over it can be it's own disaster in the making. I used to worry about this too, but you'll get over it in short order.
In the long run, any fretless board with flats or rounds, will develop witness lines of the string's imprint. Either way, you're firmly pressing a vibrating, tensioned bit of steel against lumber (or composite, like the EUB in my avatar). Marks will be made. Play with full force. Abandon any sheepish tendency, or you'll develop a dislike for the instrument if you feel you're playing on eggshells. Once you get over the first few witness lines on that fretboard, you'll be just fine.
Bet you can't wear it out in your lifetime.
Finally, I have to say, respect to that builder. I really like the artful way the fret lines have been laid out. 5 stars for style.
