Based on the advise of the two fine gentlemen that commented earlier I have done extensive merging of places and place details. I've found that using DataClean, Places first tidies up the names in a more "bulk" fashion and makes the resultant merge easier. It's quicker to clean the places and place details using DataClean than to individually use the Split Place Details on the Place List. I admit I would have never figured out how to merge place details without their assistance.
First off remember that there are no GDPR regulators sweeping through web sites looking for violations. An EU citizen or non-profit will need to contact you (or have already contacted you) and asked for details about your data and what you do with it, or asked to have data about themselves removed or changed and you failed to respond. So it's long odds and I would not shut down your site or anything drastic.
Now it would be really cool if RM would have a boilerplate page you could tweak, since the ways we all get out data, process it, and share it are pretty common.