Rentalot Plus is fully, natively, multi-language. You do not need any other software to make a multi-language site.
This demonstration site is not fully translated and does not fully exploit all of Joomla's multi-language features like article and menu item associations. On this site we are only demonstrating the multi-language capabilities of Rentalot Plus, not the whole of Joomla.
Creating and maintaining a fully multi-language site is a lot of work.
If you do decide to create a multi-language site, the Rentalot Plus translation interface is very easy to use. Everywhere you configure any text, language tabs appear so that you can enter the text in all of your site languages. It couldn't be easier.