I have an Alpha ply tpo roof on my Starcraft tt. When we purchased it back in 2013 I contacted Alpha to see if Dicor products were safe to use on it as the Alpha products are very hard to get a hold of. I was told it was no problem and we have resealed a couple areas with Dicor with no issues. As to the Eternabond, I do have a roll and have used it to seal a cracked skylight. Haven't needed to use it directly on tpo but wouldn't hesitate to do so.
Fyi, Murphy's oil soap was recommended by Alpha for cleaning.