They are expensive, and are basically a bucket of goop and some scrim tape. They also include a corner seal tape, which is a sticky rubbery sheet, but you don't need this unless completely retiling the whole lot.
A squodge of acrylic sealant into and around the screw holes before screwing should do the job. Don't use silicone or the tile/panel adhesive won't stick. Just stick a square of standard plasterer's mesh scrim tape over them, or don't bother at all if using panels.
No idea about rigid panels though. Presumably just glue to the timber frame and hope for the best? Probably not a good idea as your mixer valve will be applying a load, even with a supporting timber frame.
A squodge of acrylic sealant into and around the screw holes before screwing should do the job. Don't use silicone or the tile/panel adhesive won't stick. Just stick a square of standard plasterer's mesh scrim tape over them, or don't bother at all if using panels.
No idea about rigid panels though. Presumably just glue to the timber frame and hope for the best? Probably not a good idea as your mixer valve will be applying a load, even with a supporting timber frame.
