I'm looking for some advice. Anyone done a Triathlon build?

After searching through lots of open mould frame retailers for a triathlon frame i think i have found a good one. TT912 in T1000 carbon. (i don't trust the chain stays on the TT915) So originally Tan Tan but i can see it on sale quite a few rebrands.

I'm trying to order to the UK. I'm not sure which retailer will be best or which store to use. Winow, Mira, Falco, Haideli or Seraph.

I'm surprised i don't see any TT/triathlon builds on here. Any other advice on frames?
The Rinasclta / Airwolf TT YFT058 geometry looks limited for me (im halfway between medium and large)
The ICAN TT012 TT016 frames have a lot of stack similar to road bikes which is a bit strange. Almost like they quickly redesigned a road frame. I think this is the same with the Winspace TT1550 frame. A few brands are still pushing Vbrakes.
Velobuild VB-TT-023 seem to have a good frame. Looks like they accept orders direct from their website but i think i prefer AliX.

im currently building my TT912.
On TanTan insta, you'll see an icecrack blue TT912 few weeks ago. thats my frame.
However you'll noticed that the cockpit is different. I swapped from integrated basebar-stem to a split part referencing Falco bike parts. Thus the fork cutout under the stem is different than advertised TanTan 912

I ordered mine via TanTan website contact info whatsapp, n had it shipped to SG.

Honestly, if you live in the UK check Facebook marketplace triathlon buy sell groups. There are some really good builds on there for great prices. I'm not sure a open mold will be nearly as good.

Velobuild TT23, size recommendation

I usually have 56 size on S-Works or M in Canyon which fits perfectly, but I'm not sure about this bike.

Can you please recommend

Thanks