Did you get any further with this? I had a cheapie Tri bike for 10 years and upgraded to a nice one when I was stepping up to full distance. I can’t quite believe but that was 2015.
What I did, and would do again in a shot, was see a bike fit specialist in advance. He took all the various measurements and compared them to the geometry of basically all available bikes. We narrowed it down to a handful where my key geometry measurements sat in the middle of a given size. I.e. where I was on the cusp of L and XL we discounted, where I was bang on in the middle of an XL then that went on the list.
After purchase I went back to have everything set up perfectly. It was a road bike and I had tri bars fitted as part of that session. (Almost of my riding is around the local hills so a road bike+bars was more preferable to a TT bike).
The initial fit for done on a Retul bike. It is basically a fully adjustable stationary bike (looks quite like a Kickr!) so they can nail down exactly what is right for you. They film you and measure everything from every angle.
The bike I ended up with I’ve had now for 5 1/2 years now and it has never once caused an issue. I revisited the fitter once a couple of years ago to get things checked and we made some minor tweaks but the whole experience was excellent. I would recommend wholeheartedly.
I hope that helps.