I'm currently in the process of writing a story which will be setting up this combined AU, the idea I'm running with is that certain beings which the Equestrians would view, and worship, as gods (Fausticorn being one of them), are in actual fact the great beings of G1 Bionicle lore.

Up to some 500'000-1'000'000 years ago (pick at the readers discretion) the world which lands like Equestria inhabit was in actual fact Spherus Magna. but the great beings, being the bat shit insane great beings that they are, decided to force something of a reset, start on a clean slate, so they could continue to experiment and play god, this time with pure organics.

so they vastly shifted the plate tectonics, but rather than committing omnicide and eradicating everything they bunched all of the bionicle races (which for the sake of lending some sort of lore I shall be referring to as "Spherus Magnans") together into a belt like region on the bottom half of the southern continent, cut off from the rest of the word by a buffer region of dense jungle, harsh desert and treacherous mountain ranges inhabited by all manner of fierce monsters (read as dinosaurs), although it's not impossible to traverse it's difficult enough to put off most who would want to try.

this is the world of "Terra" as it stands in the "current era" of the story (set just after the season 4 finale)

focus in on the far south-west and you'll see the following pocket of nations, what I'm referring to as the "Matoran-Agori Alliance", the land labeled as Destral is inhabited by a new race of Makuta lead by Miserix, none of the deceased makuta from the original lore are reoccurring in this nation before you ask.

but everything to the east of that is a blank slate, which is the reason I'm making this post in the first place.

I'm taking ideas and suggestions for nations, regions, and the races that inhabit them, they can lend from G2 lore as well as G1 lore, or they can be something totally unique and new, but still in keeping with the themes of Bionicle.

so yeah, go nuts

6704202
The Koro, Wahi, and Metru could work. Wahi for between major areas, Koro being smaller cities, and Metru for the larger cities/capital if you want city states. Beyond that could lump them into related things like Fire/plasma/iron living in one area so that would be TaSuFe: -Koro, -Wahi, -Metru. play around with that.

6704266
Matoran areas are already accounted for in the MAA in the form of a "Rohe" (Maori for "area" or "region"), not so much a city as something larger, more of an administrative region like a county or burough.

the "Centralem Locis" is not so much a single city as an entire country filled with cities interspersed with industrial districts (note the locations like Nynrah and Midak).

Meanwhile the six surrounding Magnas are each devoted to one of the six primary elements, though they also have other similar elements which are likely to fit in, for example Bota Magna has Le-Rohe as well as Bo-Rohe, whilst Uro Magna has Ta-Rohe as well as Su-Rohe

following discussions with some close freinds I've managed to fill in the blank spaces with enough nations to lend a resonable diversity without getting swamped with a bajillion and one nations that I have to provide a backstory for. thinking of going for "Solum Magna" as a label for the collective regions

the West

And the east (still a few locations to add, but the key borders are in place)

Saltus Magna and Tesca Magna are vast regions of forest and arctic tundra respectively, and by vast, I'm talking about Tesca Magna being some 2.1 million square leagues (a leage being the distance taken to travel by foot in the space of an hour, the USA for example is only 1.7 million square leagues

on the subject of location names being reused, I figure that following "The 2nd Great Cataclysm" the various races would have wanted to resettle in places that had a degree of familiarity and nostalgia to them, same reason a lot of place names in the US are actually duplicates of locations in Britain and other parts of europe

6704652
fair point looking good so far