The export filter allows one to work in my opinion (I used it a bit, I picked up feelings from discussions of others). The import filter is limited (I have read that any LaTeX import filter is limited because of LaTeX's grammar), and in my judgment of this moment (that is, with very limited experience) it may work only if the people you are collaborating with "collaborate", keeping within the set of LaTeX expressions that TeXmacs recognizes. There is work which may be helpful: https://www.texmacs.org/joris/latexconv/latexconv.pdf but I do not know its current status and may not be relevant if people that write LaTeX code use syntax (e.g. a package) that the TeXmacs import filter does not support. By the way, on the topic of using TeXmacs for one's work, I picked from someone the following suggestion: presentations, they usually do not require collaboration.