Please let me know if I didn't understand correctly. What if you used a `Subscript` wrapping a `Superscript` instead of a `Subsuperscript`?

 Subscript[Superscript[x, 4], 2]

![Mathematica graphics](https://i.sstatic.net/JVUCz.png)

Its `TeXForm` gives `x^4{}_2`. Does that render as you want?