Interesting....learned more.
Currently am using a helper function to convert Tex to Mathematica:
getTex[eq_String] :=
NotebookWrite[SelectedNotebook[], ImportString[eq, "LaTeX"]];
using it like this:
getTex@"- Set of natural numbers: $\\quad N =\\{0,1,2,3, \\ldots\\}$,
- Set of integers: $\\quad Z =\\{\\ldots,-2,-1,0,1,2, \\ldots\\}$,
- Set of rational numbers: $\\quad Q =\\left\\{x \\mid x=\\frac{p}{q}\
\\right.$ with $p \\in Z , \\quad q \\in Z$ and $\\left.q \\neq \
0\\right\\}$."
This code has given the most stable direct easy way to convert TeX via copy and paste. The kernel asks to escape things when needed. Am open to suggestions to improve the code. And I wonder if there are other Tex stuff it fails to convert correctly like log. Is there a test bed to discover other exceptions? Thanks.