I've just used Broken Link Checker quite successfully to find and fix links to my event calendar after I made an update that caused all their slugs to change, thank you.
But I found the following bug when a particular broken link is found in multiple posts with different link text. In this case, Broken Link Checker cleverly collates these as a single broken link in the list, but shows the link text as "(Multiple Values)" greyed out. That's good... but if I want to fix the URL, but leave all the link texts as they were, I thought I could just change the URL and press Update. Unfortunately, I found this results in all the link texts being changed to "(null)". :-(
Sometimes links I make (e.g. in the middle of a sentence) will have different text even though they're the same link target, in order to fit the text flow. I've manually fixed up all the nulls that Broken Link Checker introduced, but it'd be great if this bug could be fixed.