W ten Wigilijny Wieczór niech opłatek i staropolska kolęda połączą nasze myśli i serca, a uśmiech niech towarzyszy wszystkim dniom Nowego Roku.
May wafers and traditional Polish carols unite our thoughts and hearts on Christmas Eve , and may all the days of the New Year be accompanied by a smile.
"May wafers and (-) traditional Polish carols unite our thoughts and hearts on Christmas Eve, and may all the days of the New Year be accompanied by a smile."
In Polish words "wafer" and "carol" are singular (it means "sth" in general), but if you think it sounds better in plural in English, I believe you, dear Lilly.
I agree with the rest of your corrections too.