I'm sure Flying Hellfish was the last mod added as the process that led to their employment was advertised. I guess that should be in 2019 or so, can't be sure of the date any more. I ain't sure mole0815 or Welsh got in after 2019. Well, sadly I don't know what became of the user. I haven't seen more of them online. I just checked their profile now and the dude was last active on July 13, 2021.
Flying Hellfish was or is moderator for longer than Welsh, I have no doubt about it. In my mind Welsh was the latest addition.
I made a small investigation with the elements I have at disposal (Staff section).
Flying Hellfish was mod before Welsh who appeared in ~July 2018 (like me, but I think I was appointed mod after Welsh).
Mole0815 appears in January 2020. And no new mods since.
But where I think there is confusion is that Welsh was first appointed mod for the Altcoins sections, then he replaced the former mod of the spanish section (and that must have been after Mole0815 was appointed).
[...there are many...], Flaying Hellfish, [...there are many...], Welsh or you, and Mole0815.
In any case Mole is the latest addition which can be told clearly. For some reason I had Welsh in mind as our latest mod.