I stand corrected! (Thwarted by phonetic spelling, ha. ETA: Ha, I just saw that Blanning even mentions him and quotes some of his Fritz-related reports (via Carlyle). Did not remember that.) But that's good to know. Even if he didn't actively try to make anything happen, I can easily believe that Suhm was in favour of the English marriages and that FW would find him suspicious, particularly if he noticed that Suhm was friendly with Fritz. And as you said in another comment above, he really did get out just in time. If FW thought he was working with the English in 1729 already, true or not (FW's paranoia is certainly not enough evidence), it would not have gone well for him in 1730. No wonder FW called him an arch villain whom he should have hanged in 1737, and that Fritz and Suhm had to take some precautions with their correspondence.
... but now I'm wondering what it must have been like for Suhm to follow the whole 1730 drama from afar. :(

what we call "diplomatic" in English: phrasing things so as not to give offense

Same in German. :)