@V A H K I T I
Trust me, I know tris are considered the devil in modelling of this variation, though I was just taking into account a few different things which lead me to doing what I have. For example, Having a vertex in the center of every circle increases the total number of tris on the model, and I was doing my best to make sure this wouldn't be TOO intensive on Stud.io if loaded in. Granted, I'm sure when I toss it to those guys they're going to condense the poly count to make a slightly more clunky-looking version you actually BUILD with, and have the model replaced with this one when you export, or render the build. I might want to send them my own lower-poly version just so they don't butcher it like they have with, for example, some smaller curved slope parts where the sidesdon't even line up with the curve, sometimes, and you see through it.
Also, the reason I even use tris in my topography at all is because when it comes to quads I always have one issue I can never get past, and that's quads splitting themselves in a way that ruins the shape. Say I need a curve, I make a quad, move the left top, and right bottom vertices backwards, I want the two front fertices to think "Ah, cut here." Instead, though, the two backward vertices think "Ah, cut here" and cause the simple two-tri shape to now become a ramp by dipping inwards instead of sloping outwards. The only way I know how to manipulate that shaping is to force it to by cutting the tris myself. In the end, with my experiences, when you texture map the mesh behaves like it has tris with how it stretches the textures anyhow, so I honestly have learned to get past it.
In short, yes, quads look nicer, and clean up a mesh more, but tris give me more control, if that makes sense.