Tanking a wall

[Odds]

My bathroom wall needs professional help and i wonder if it should be treated with Aquaseal or something like that, to protect it from further decay.
I intend to fill the holes and plaster the cracks, then erect back-boards to tile over, so that should give a layer of protection from the shower but i'd like to know if using a treatment on the bricks is a good idea or just pedantry?

 

[blup]

Don’t treat the bricks they need to breathe

Blup

 

[Odds]

Pedantry it is, then.

 

[tell80]

Your pic is too blurred and too limited to be of much use but:
The brickwork is loose.
New pics would help if you want more suggestions for the walls in the pic, and perhaps the bathroom in general?