It seems UQ Holder may be in for some censorship much like it's predecessor.
According to Egmont Manga's site, the German publisher for UQ Holder, it seems volume 13 is due to receive an alternate cover.
What's interesting is just how different these covers are. So far, they've represented what was happening in the volume, but it seemed like the idea was abandoned and instead opted to go with a previous plot-line. This "new" design is actually the backside of volume 10's cover art, however, the design is not yet finalized and may change in the future. Negima was not estranged to censorship, as seen by the censored covers for the standard and limited edition releases, so it's not absurd to think they'd make a change. It's a strange choice to simply go with a completely different design rather than adding clothes to the naked character.
Another interesting point is just how early they managed to nip this in the bud. Volume 10 hasn't even been released and this particular volume isn't due to release until March, 2018 in Germany, so it may have been obvious from the start that this cover would have issues outside Japan. There's definitely a chance this change won't just be limited to Germany either.