Honestly, I share the same view, the period of Romanization was too brief to profoundly influence a people that was not fully conquered. It’s likely that the European region benefited from a dialect continuum that facilitated, to some extent, mutual intelligibility. If you’re curious about this topic, check out "No venimos del latín" by Catalan author Carme Jiménez Huertas (in English, "Romance Did Not Begin in Rome"). It explores Romanization in the Iberian Peninsula, with insights that also relate to Romania and Romanian.
https://www.amazon.com/Romance-Did-Not-Begin-Rome/dp/1984030213
Regarding the cataclysm you mentioned, yes, there are theories suggesting that the Black Sea was formed by a catastrophic event, forcing populations to migrate westward. Interestingly, the emergence of agriculture in Europe may even be linked to this westward population shift from the east.