The polyeurthane epoxy, I forgot it was flexable. Oops, lolPU (polyurethane / “epoxy” ) is what you want to use. Expands through whole depth of crack and can be used in a wet location; if dry than mist with water before injection.
Grout the tubes in place and make sure it is set before you try to inject or the expansion will pop the tube off the wall and the PU will leak out.
You can do this, it’s really straightforward and has maybe 4-5 steps total. Wear disposable gloves when injecting…it will get on your hands