Here are a few tips.
The wiring is not like doorbell wiring. Low Voltage lighting that operates at 12V or 24V has a lot of current - 10 times that of 120V lighting, current causes wire to burn. So the installer needs to keep that in mind and gauge the wire properly
Certain transformers are UL listed to be recessed into the wall, they need to have an IC rating, but they can achieve this if desired.
n mind and gauge the wire properly
Never hide a transformer in a wall or ceiling space that will get covered with paneling or drywall. The transformers must be in open view so they can be serviced or replaced. Keeping them in the open helps provide the needed ventilation. You can place them above dropped ceilings so long as the ceiling tiles can be removed and the transformer is in plain sight.