Just in case that it is not omitted I submit it (it is bugfix but Yoda asked to submit)
- Ukraine did not exist in 1648: Donetsk to Russia, Ukraine, Poltava and Krementjug to Poland (and fortress level 2 in Ukraine is ahistorical, since much better and bigger fortifications were in Podolia)
- Khmelnystky uprising started in spring 1648
corrected dates of events dealing with uprising were already submitted
and are here (description of first event in fact describes reasons of personal grudge of Khmelnytsky but not why uprising has broken out)
extra:
- some stuff dealing with Union between Orhodox and Catholic churches: two events have been merged and change of province culture to ukrainian was proposed to be delayed
here and
here
culture changing events have been made province specific.
- some discussion about Ukraine was in above posts, posts 711-721 and earlier 693-695; generally I have expresses opinion that UKR tag could be freed; there were some questions but no opposition nor (real) discussion
uprising started in 1648, from late 1649 (Zborow agreement) one could consider Ukraine autonomous and self-governed. In 1651 this autonomy was broken. Due to lack of successes, plague and general waste of provinces in 1654 Cossacks asked Tsar's protection (document is lost so nobody knows details). Russian troops entered and uprising changed into war between Poland and Russia. In 1658 Cossack leaders decided that Poland offered better terms than Russia and signed Hadiach agreement with Poland. Some revolted against it so there was extra Cossack civil war. In 1659 pro-Russian Cossacks signed second agreement with Russia, which limited their autonomy significantly. In 1667 Poland seceded Poltava and Krementjug to Russia. Pro-Polish Cossacks stayed in poland, pro-Russian moved to Russian part of Ukraine.
So no independent Ukraine for sure after 1659. Neither Russia, Poland nor Ottomans/Crimea would tolerate it, as Cossacks were even more anarchic democracy than Poland.
About 1672 Ottoman Empire got southern Ukraine and also did not free Ukraine, just gave them some limited autonomy.
Edit:
more detailed events but not submitted since I am still working on it