No simple way to do this. I suggest you may try to toggle the visibility of 2 columns and add the onChange event to make necessary changes. Anyway, I will consider to add the focus or double-click event in the future.

I gave up on this idea and went with another solution. Here is what I did:
I used another json to keep the formulas and listened the cell-focus event. I found the corresponding formula (if there is one) when the cell-focus event occurs then showed it in an input field above the actual table. This also makes it possible to edit the formula. If it is changed I execute it and write the outcome back to the data.
Thank you for considering adding new events I think it will be better.

Yes, you may also use get set variable in javascript. Will follow up about adding events