If at any time any muriatic acid vapor present in the air has been deposited in an electronic device, what should I do to ensure that this deposited vapor does not remain permanently on the circuit board and metals corrode?
Protect parts that may be damaged by water (fewer than you might think), and then wash thoroughly with warm soapy water. A trip through the dish washer (set to air dry) can be quite effective.
Does the pure concentration of dilute muriatic acid have any influence on the evaporation generated and does this vapor fall over the circuit boards and always remain?
It's that guy who thinks everything is falling apart.
You should do nothing but evacuate the area immediately. Electronics are more robust than humans and any amount of time that you remain there is going to kill you long before it does anything to your electronics. The exception is water. Humans are more waterproof.