He was a fervent supporter of Esperanto, and starting in 1923 became a long-time instructor of the language. Reportedly, he addressed the 1970 World Congress of Esperanto which was held in Vienna with perfect Esperanto.
In 1974 he died in office.
In Vienna, a large tram station officially called Schottentor which was built when he was mayor is colloquially named after him (Jonas-Reindl, which translates as Jonas bowl).