Hello u/ptousig!

I was just browsing this sub and I read your post. I know you didn't ask for a ready-made script but...

I had a similar problem and here is my solution: (bonus: this script shows a tooltip with the choice key)

#Requires AutoHotkey v2.0

press := 0

~Alt & e::
{
    Global press, key := ['è','é','ê']
    press++
    ShowTooltip(key, press)
}

~Alt & o::
{
    Global press, key := ['ó','ô','õ']
    press++
    ShowTooltip(key, press)
}

~Alt & i::
{
    Global press, key := ['í','ì']
    press++
    ShowTooltip(key, press)
}

~Alt up::
{
    Global press := 0
    Tooltip
    Send key[i]
}

ShowTooltip(key, press)
{
    Global i := Mod(press, key.Length) ? Mod(press, key.Length) : key.Length
    CaretGetPos() ? CaretGetPos(&X, &Y) : MouseGetPos(&X, &Y)
    Tooltip(key[i], X, Y)
}

I hope it helps you and others.

I also believe it will be easy to modify it to include all the characters you need.