Since the cracks are purely cosmetic you can use caulk to cosmetically fill the cracks. Do a small test to make sure the caulk visually meets your goal.

I am definitely not a pro, but if it is a large portion of the floor and staying wet for a week+, then I would say yes. To me that would indicate a good amount of water not draining and standing water with no place to go is never a good thing. Alternatively if it is that the ratio of water was incorrect when mixing the grout, then the grout will be weak and crack/crumble fairly quickly. As I mentioned in some of my comments from my original post, after 2 years with our contractor we gave up as they were useless, but our area at the end of the process was relatively small and it was clear they were not going to fix it. I would press hard for them to fix the problem, it really is the right thing to do. May require them to rip out the floor and pan, but a good contractor should accept that and you will be much happier.

I might be using Crossville's Virtue throughout the whole small bathroom. I was thinking of using their hex with a darker medium warm grey on the floor, and matching grout everywhere else. Also considering using their brick in half height with a little darker grout and then a matching grout on the same tile in the bath surround. There will be the shower glass separating them. Would it look better all the same grout? Wanted to delineate the brick but didn't want a grid patter around the shower. Floor will be a medium taupey color if I do that scheme.

I bought the 15 boxes of tiles at Lowe's. Waited for them to pull them off of a pallet with all the same lot number. Went to do other stuff. Went back to Lowe's. Gave up after 45 minutes. Told them I would be back later that night. Called them mid afternoon to make sure the tiles were pulled. They said they were. Went back at 6:30 p.m.. Not pulled yet. I ordered 10 more boxes for the other bathroom. Waited a half hour, then told them I would pick them up Tuesday morning. Went this morning and they were still not pulled. I left while they pulled the tiles, and went back after lunch. Still not pulled. I waited a half hour, then got a refund of the $625.00. Good grief! So, I will be looking for a new tile, probably 12" x 12" or maybe 18" x 18". That is the largest tile I have ever set. No problems whatsoever with it. I just have to find the right tile that I can set. No tile pros around here, just people who tile and say they are pros. Been there...done that. I can do better than the pretend tile guys around here. Very, very rural area! I still have drywall texture to fix that a supposed pro did. I paid someone else to fix it, but it still looks bad. Not paying a third so-called pro. I will learn to do it myself. Wish I lived in a larger town with actual pros!