Back and forth conversion is not fully supported, we try to have good match (see e.g. https://www.texmacs.org/joris/latexconv/latexconv.pdf ). TeXmacs has its own format, so no: you cannot collaborate with people which want to edit LaTeX files. But you can convince them to use TeXmacs. :) I've never regretted. I go back to LaTeX sometimes but most of my documents are now created in TeXmacs. If you need a tool to collaborate then use things like Lyx or TeXstudio, etc... We had to get away from TeX to remove the intrinsic limitations of that technology. There is not much you can you if you want to stick to complete TeX compatibility.