Hi Dolce Vita.
One way is to create the toc on a non-printing layer.

I am completing a project that has two tables of contents, one in English, the other in Japanese. The TOC currently looks like this:

English is on one side, Japanese is on the other.
The pages that hold the TOC text only have placed Illustrator files. While a single English letter appears on the page, that letter is present in the Illustrator file so InDesign will not format or read it. The print-view of the page looks something like this:

The overprint view, however, is quite different because it displays a lot more information:

In the middle-left area, there is a small a and ?. Those characters are in a text frame that is on its own non-printing layer. Another text frame holds the AIUEO ????? A ? text.
In my case, because I am working with two completely different languages, I have also created two additional sets of paragraph styles, obviously one for English and the other for Japanese.
It has been quite a bit of work to put this together, but in the end it’s been worth it.
Good luck with your project.