Hi @Anais ,
The wireframe feature in in uMake always display a 4*4 wires on the surface for a topological surface (like the one in your photo), this number does not reflect the number of triangles that are exported during obj export. You can use the wireframe feature to validate the number of triangles of a triangulated surface (like those imported from an obj/stl files) If you will load ‘Un cube classique.obj’ to uMake and display the surfaces as wireframe you will notice each surface have only 2 triangles. Like shown in this image
You can also validate the number of triangles by opening an obj file in a text editor, when I did it I noticed each face of the box have exactly 2 triangles.
So there is no other way to interpret this rather than a problem in ‘Unfolder’. I guess that there is some import configuration that pumps the number of triangles. My advice is to send their support/forum the obj file you uploaded here and to ask what is the reason for what you are seeing.
I am sorry I couldn’t supply the full solution to your problem, and will be happy to help if you will have further questions.