I took a look through the Mechanical family and came up with these subcategories:

Mechaspider
Carcinized Zerethsteed
Scrapforged Mechaspider
Crimson Shreddertank
Enterprising Shreddertank
Mechagon Peacekeeper
Rusty Mechanocrawler

Chopper
Champion’s Treadblade
Chauffeured Mekgineer’s Chopper
Hateforged Blazecycle
Mekgineer’s Chopper
Mechano-Hog
Incognitro, the Indecipherable Felcycle
Chauffeured Mechano-Hog
Warlord’s Deathwheel

Mechsuit
Diamond Mechsuit
Lightforged Warframe
Machine Defense Unit 1-11
Asset Advocator
Blackwater Shredder Deluxe Mk 2
Crowd Pummeler 2-30
Darkfuse Demolisher
Felsteel Annihilator
G.M.O.D.
Junkmaestro’s Magnetomech
Personalized Goblin S.C.R.A.P.per
Stonevault Mechsuit
Venture Co-ordinator
Violet Goblin Shredder
Rocket Shredder 9001

Rocket
Geosynchronous World Spinner
Lunar Launcher
X-45 Heartbreaker
X-53 Touring Rocket
Depleted-Kyparium Rocket
Innovation Investigator
Ocher Delivery Rocket
Steamwheedle Supplier
The Topskimmer Special
Thunderdrum Misfire
X-51 Nether-Rocket
X-51 Nether-Rocket X-TREME

Mechacycle
Mechacycle Model W
Junkheap Drifter

Shredder
Mechanized Lumber Extractor
Sky Golem

Aerial Unit
Mimiron’s Jumpjets
Rustbolt Resistor
Aerial Unit R-21/X
Bilgewater Bombadier
Darkfuse Spy-Eye
Margin Manipulator
Mean Green Flying Machine
Prototype A.S.M.R.
Salvaged Goblin Gazillionaire’s Flying Machine
Zereth Overseer

Flying Head
Mecha-Mogul Mk2
Mimiron’s Head
The Big G

Pirate Ship
The Breaker’s Song
The Dreadwake

Waveshredder
Bronze Goblin Waveshredder
Soweezi’s Vintage Waveshredder
Pearlescent Goblin Waveshredder

Airship or Flying Machine
Darkmoon Dirigible
Delver’s Dirigible
Delver’s Gob-Trotter
Stormwind Skychaser
Orgrimmar Interceptor
Flying Machine
Turbo-Charged Flying Machine
Explorer’s Jungle Hopper

Trike
Goblin Trike
Goblin Turbo-Trike
Vicious War Trike

Mechanical (these can probably stay as Mechanical)
Meat Wagon
Wonderwing 2.0
X-995 Mechanocat
Flarendo the Furious
Xiwyllag ATV

These look really good. A couple will be difficult to translate since the name isn't in any wow text I can try to use wowhead for the translation. I'll see what I can do

OK after a few tedious hours of data lookup and entry I think I have this done. It's not 100% exactly what you listed, but I think 95%.

You can see the changes at a368e7a

Wow! It looks amazing! Thanks for working this in so quickly! The category names all make sense to me!

The only change I would consider is some of the mounts you put in the Shredder family. The 'Blackwater Shredder Deluxe Mk 2' and 'Violet Goblin Shredder' do have shredder in the name, but the models are definitely the same rigs as the other Mechsuits like the Lightforged Warframe. They're also just recolors of the other goblin mechsuits added in Undermined.

I also originally had the 'Rocket Shredder 9001' as a Mechsuit, but it also works as a Shredder. I think it's model is unique, so it could go either way.

Thanks again for doing this! It helps a lot for people like me who use the family filters to pick mounts that work for the lore of my different characters.

After some consideration I'm going to split these even further. Blizzard is definitely using a translation for shredder that is "wood cutting machine" for the goblin shredders in other languages, but they are distinct looking. Honestly even now I think it's possible Shredder and Warframe could be merged, and you could roll a die and put Rocket Shredder 9001 in any of the boxes.

LM.MOUNTFAMILY["Goblin Shredder"] = {
    [466023] = true, -- Asset Advocator
    [466019] = true, -- Blackwater Shredder Deluxe Mk 2
    [466018] = true, -- Darkfuse Demolisher
    [468068] = true, -- Junkmaestro's Magnetomech
    [466020] = true, -- Personalized Goblin S.C.R.A.Per
    [466022] = true, -- Venture Coordinator
    [466021] = true, -- Violet Goblin Shredder
}

LM.MOUNTFAMILY["Mechsuit"] = {
    [448186] = true, -- Crowd Pummeler 2-30
    [458335] = true, -- Diamond Mechsuit
    [448188] = true, -- Machine Defense Unit 1-11
    [442358] = true, -- Stonevault Mechsuit
}

LM.MOUNTFAMILY["Shredder"] = {
    [223814] = true, -- Mechanized Lumber Extractor
    [400733] = true, -- Rocket Shredder 9001
    [134359] = true, -- Sky Golem
}

LM.MOUNTFAMILY["Warframe"] = {
    [182912] = true, -- Felsteel Annihilator
    [289083] = true, -- G.M.O.D.
    [239013] = true, -- Lightforged Warframe
}

Thanks again for doing this! It helps a lot for people like me who use the family filters to pick mounts that work for the lore of my different characters.

I feel sorry for you! I am just making this stuff up.

p.s. If you are bored feel free to go through the families and suggest more fixes.

https://warcraftmounts.com can be helpful to see things with the same look, though they are making it up by hand too and often have mistakes or miss things.