I've released a Flagfox 5.2.4 update, primarily for Firefox 52 ESR, but it'll work in anything else Flagfox 5.2.x runs in. You can get it here:
https://flagfox.wordpress.com/2018/02/28/february-updates/

(Just FYI: Even after I eventually discontinue providing these updates, I have no plans to change the IPDB file format any time soon, at least not likely in a backwards-incompatible way.)