I don't think so. Volume 5 is going to contain chapters 37-46 if they stick to their 10 chapters per volume scheme. That's the last half of Eito's adventure in the girls' bath, Eito's attempt to find out his nameless roommate's name, and the story of the Phantom of the Basement.
This future pink think looks like a contiunation from the one in volume 4 >>2277197
because both volumes contain parts of the bath adventure.
He might eventually add a bath fight scene to the omake chapter, or he could release a colored version as quiz bonus, but I don't see it coming up in any regular chapters in the near future. At least I hope so, because, while I enjoy the PLOT, I'd prefer if he'd advance the plot a bit more instead of giving us too many fanservice chapters.
I wonder if the publishers intentionally release their ebooks in horrible quality and with extras missing to make the readers buy the print version.