Odd rough-in distance

I'm thinking of buying two Toto Nexus toilets for myself, but measuring the distance from the wall to the center of the bolts in my current toilets gives 11.5 inches. Will the Nexus fit regardless?

As a side question, the floor is tile with what is probably concrete underneath. I know that 4 holes are needed for the Nexus, but are there any issues in securing the anchors to this type of substrate?

Thanks!

The Nexus will work with 11.5"
It only takes four holes per toilet in the floor for the Nexus adapter.
A 5/16" hole works with the tile, or a 1/4" will work if you move the bit some.

Depending on the tile, a diamond core bit may be the best choice for drilling holes (some tile is extremely hard). You can buy them on-line, Lowes carries some made by Hitachi that aren't too dear for the smaller sizes, or a tile shop. Other types of bits can be used, but this will certainly work rather than trying one and finding it doesn't even mark the tile, then having to buy something else.