Apparently there was an international conference of all the leading accordion teachers some years ago with only one goal: to agree on an international standard for fingering notation so that the accordion could enjoy the degree of consistency of other instruments for music publishers. You can guess what happened - the conference ended with no agreement and the universe of one remained the status quo!
To add yet another way of fingering notation, my cheap scoring programme doesn't do circles, lines, asterisks, pluses or amusing emojis for fingering, just the bare number. My solution was to change the colour of the notes when they are on a helper row. I personally find this clean and easy to read rather than a system that looks like ants have been fighting on the page. Doubtless it would have provoked bloodshed at the aforesaid conference!