This caused by dampness inside the bathroom. It would appear the bathroom walls and floor were not waterproofed. So, moisture travels from the bathroom through the all to adjacent rooms.

The solution is to remove the tiles in the bathroom, waterproof the walls and floor and relay the tiles.
Better ventilation of the bathroom is also necessary.

Ask your builders to develop a full schedule of their requirements including prices. This should be broken down into work packages for example foundations, walls etc.

Together with the above they should have a program indicating what activity will be done when.

Armed with this information you can make your cash flow projections.

The floor gradient is wrong. Depending on its severity, you can remove the floor tiles, and set the gradient on the cement screed right. The relay the tiles so water flows into the drain.

Plan properly so work is sequenced according to proper building practice. This way you avoid cutting and related damage to completed work.

The builders should have regular planning meetings to identify activities for the coming week/month.

Shopfronts and areas with large panes should have safety glass. When safety glass shatters it acts the same as car windshield and should not cause injuries.

Are there trees nearby? Their roots may have gown towards the foundations and the expansion may be the cause. If this the case, have the roots/tree cut. Then redo parts of the damaged wall.

Long boundary walls should have vertical expansion joints to allow for the expansion of the construction materials. Check if you have expansion joints every 3 m. If not, then you have to introduce them.

Check the ground condition. Subsidence of the soil will cause movement which in turn cause cracks

Some of the tiles should be applied using a bonding agent in addition to mortar.

Also, certain types of tiles should be laid on insitu cement/sand screed( i.e. when the screed is still in its plastic state)