This market will resolve after Romania is fully allowed to enter the Schengen area and resolves to "Yes" for that year.
After a year has passed, which doesn't see Romania fully join, that year will be resolved as "No".
If there's no Schengen, this resolves to "N/A" for all unresolved years.
This market will prolong indefinitely. The market close date is there to help me close each unsuccessful year.
Related: https://manifold.markets/FlorinSays/when-will-bulgaria-fully-join-the-s
Related questions
Romanian Prime Minister Marcel Ciolacu welcomed the partial entry agreement.
"From March, Romanians will benefit of Schengen advantages on air and sea routes," he said. "I am convinced that in 2024 we will finish negotiations for land borders as well." -Reuters
I assume "finish negotiations" is not sufficient to resolve this to 2024, but it is about the actual border controls.