Is it necessary to clean underhood relay and fuse box from dusts?

A little history:

My Chevrolet Aveo 2007 got into a strange state where it cranked, but did not start. It also had P0340 (Camshaft Position Sensor Code). Since, I did not see stable 12V on the Pink wire to the Camshaft Position Sensor, then one of the users on this site suggested to connect Battery+ directly to the Sensor’s Pink pin and to try to start the car then.

After doing as suggested, the car successfully started. And even more surprisingly, it started even after I removed the Battery+ wire and plugged sensor back into its designated harness.

Problem description:

Having said that, it seems that there was some kind of “memory effect” where “something” was preventing stable 12V to show up on the camshaft position sensor’s pink wire. And that “something” disappeared after I connected sensor directly to Battery+ just for one crank attempt.

The effects visible on the Pink wire when issue manifested itself were:

1. After turning key to ON, but not cranking. The voltage on that pink wire was slowly growing on average for 10 seconds from 2V to 12V. Then it stayed at 12V. I was even able to connect small load (6x20miliAmps LED lights in series) between sensor harness’es Pink and Black wire and they stayed lit up.
2. At the time of cranking the voltage on that pink pin dropped from 12V and then bounced between 0V to 2.5V.

Question:

While the car starts, I don’t want it to run into the same issue again. Hence my question is – can battery caused corrosion dusts get into fusebox where relays and fuses reside and cause such strange electrical issue as I described above? If yes, then how? Or, perhaps, I should still look for the root-cause somewhere else?

As a reference here is picture of my underhood fusebox that show those cyanish colored spots that I plan to clean away. Note that the “Main relay” which supposedly is responsible to deliver stable 12V to the camshaft position sensor resides in the area most exposed to those dusts:

P.S.

The car has had some other electrical problems that may or may not be related, like:

1. AirBag light mysteriously on for 3 years. Dealership read the codes but did not find anything. Just told to change battery and other stuff and see if it goes away.
2. The rear right signal light misbehaving. Though for this one I am suspecting a broken wire in the rear because there was clear correlation between moving harness and blinker working again.
3. The battery has slowly drained few times in the past.