I just recently purchased a Soma Lyra8, only have had it for a few days. So I am pulling all the levers to listen what happens. From your explanation, yes. The «35>56 78>12» switch in UP couples «Banks 1 to 4 » to «Banks 5 to 8», whereas when the «35>56 78>12» switch in DOWN, only the four switches («34|LFO FB CV», «12|LFO FB CV», «78|LFO FB CV» and «56|LFO FB CV») control the FM modulation (now «Banks 1 to 4» are independently modulated from «Banks 5 to 8»).
Just by listening there appears to be some other coupling, I can’t quite place my finger on, I suspect some of that magic cross-talk in the circuit, Vlad is talking about.
I am happy to be corrected if I got this wrong.