Editing after having imported a LaTeX code

I wonder how to fix those errors after having imported a LaTeX code. For example, I paste the following code from LaTeX


I find that TeXmacs failed to parse them. On the other hand, if I import a LaTeX file including these codes, they will be verbatim. I don’t know what I can do to help TeXmacs parse. I noticed that sometimes TeXmacs parses \xymatrix. I don’t know how to modify the code so that it could be parsed by TeXmacs.