This probably won't be the best answer but you are factoring in elderly so perhaps they call in from their HOA registered phone number into a phone tree voice m

This probably won't be the best answer but you are factoring in elderly so perhaps they call in from their HOA registered phone number into a phone tree voice menu that explains options and they press a number to vote? It's still automated and mostly digital. I have no idea who would offer this service but I could see elderly being able to figure this out if the phone tree was simple and had a simple way to "go back" or "start over" or "repeat last option". Perhaps this system could even record their voice giving consent to the vote and to have a sample of their voice to verify identity. The IRS does this.