Sorry about your troubles. For the curb, I'd peel or cut off the loose Kerdi and re-do, the sooner the better. The trick with those, or any, tight corners is to pre-fold the Kerdi before applying.
The floor is trickier... does the tile move? Try pulling up on them. If the tile moves, might be a re-do. If it's just a few grout joints that look like they didn't get adhered well, I might just carry on. If you just stuck the tiles down, they might break loose if you tap sideways on em... maybe. Did you do a flood test of the pan before tiling?
edit: Well, you answered that one. Now to remove the tile & Kerdi while leaving enough down for a 2" overlap for the new piece.