Take this as your stock “old man cautioning you to turn back.” If you have any, any other avenue of getting your data other than the way you are trying to do it now, I advise you to think hard on pursuing that path first.

Tiger for what it’s worth, part of my profession is dealing with just this, taking point clouds and STLs and converting them into useable CAD data. Converting a mesh model to a proper CAD file sounds like labor Long story short, converting a CAD file to a mesh model is just a few taps like an STL export in Shapr3D. Well, what could go wrong with the conversion of a converted file With the spread of SubD modeling, another solution appeared but that results in a lot of possible inaccuracies: if the triangular mesh can be converted to a quad mesh, then it can be converted to the SubD model. If vertex snap is possible, that could help a lot, but the process will take a significant amount of manual labor. Reverse engineering can be done fully manually using appropriate surface modeling software that can project and intersect meshes. At the end of the process, the model will still not have curved edges or surfaces, but at least it will be defined as a CAD model, not a mesh one. If you give a try to any of the mesh to brep converters, you will see that they do almost the same thing: replace the mesh polygons with tiny triangular surface elements. Do not get me wrong, they are extremely helpful, but not making the process as simple as clicking on a Convert button. It mostly guides the user by helping to find planar or cylindrical surface elements by applying refined algorithms to provide fewer possible inaccuracies compared to the mesh model. Even with suitable software it can only be partially automated in the case of detailed models. Hi way to convert an STL (or any mesh file) to a CAD model that can be edited flawlessly is the process of reverse engineering.

Shapr3d manual