I pictured that even if volcanic mountains forms they'll be quickly destroyed by the erosion of the waves. Volcanic rock is notoriously weak against water, check the various volcanic island in this last 100 years that quickly(days) emerged and quickly(months) were destroyed.
1)As I said Venus' atmosphere is actually 70km even if it says 170km.
2)As I said I can't properly simulate the temperatures.
I'll fix the atmospheres and add life to Laythe.