Not sure what you mean by “seal the roof with Eternabond”? If you are referring to the tape product this would be ill advised. Eternabond is ok for small damage like an impact from a rock or branch but using it to seal large sections of the roof will be horrible for whoever needs to clean it off in the future because it does eventually lift and leak no matter what anyone says. And the problem is once Eternabond starts to leak you really can’t see evidence of it standing on the roof. Until you start to peal it back is when you can see leakage which is too late.
If I’m reading too much into this I apologize but people use Eternabond way too much because it’s easy to apply, but at the end of the day it leaks and has to be removed. Removing Eternabond that has been down for years is probably the worst material on the planet to deal with.
As for cleaning the roof use “Super Clean”. I would only recommend using this stuff for cleaning in preparation for a reseal, NOT as normal maintenance. They sell it on Amazon.