[Zeke]

Well, if we're going into a discussion about risers I think you could split the difference. I haven't run into many 5/4 risers but I'm not there and it's an old building.
1/4" ply and half inch tile board is one way to do a 3/4" hybrid. Or 1/2 ply or OSB with 1/4 tile board, either way glue it fully to make a lamination and it will stand up to use.

The thing is, those Talavera tiles can be hand made and not that flat, so with thinset you might want to plan for another 3/8ths inch of riser thickness. This could make the treads awkward. Tile selection is important here as 1/4" tile is preferred. I'd even skimp on the backer to get the tiles back under the risers enough to preserve the tread overhang. The range is generally considered to be 3/4" to 1-1/4. I prefer more rather than less but will settle for what works AND looks good. If it's too flush you will notice.

Personally, for interior stairs I need a min of 11" tread. Again, I can settle for less but at size 12 I don't like 10" treads at all. We don't know what the conditions are now so it's all talk.