Can I uninstall EW6?
uninstall EW6 in control panel & delete Easyworshipv6.1, Easyworshipv6.A9, Easyworship folder in PublicDocs & any other related files
Then reinstall EW6 & convert EW2009 data
This I would expect to put me back to early 2015
Would this work or cause more problems?

You can but you do not need to do that. You can just rename the data folder in the v.6.1 folder and this will reconvert your EW 2009 data. https://support.easyworship.com/support/solutions/articles/8589-transfer-ew-database-ew2007-2009-6-to-ew6-:26vnxo6x]Here are the insturctions