redirects

sorry should read — OK to use a redirect plugin when your plugin is running

The Premium version is already doing the redirects from the Joomla URLs to the WordPress URLs.
https://www.fredericgilles.net/fg-joomla-to-wordpress/

Right, but I have some other pages not from the Joomla I need to redirect.

Would using another redirect plugin interfere with the Joomla redirects?

There shouldn’t be any problem. The redirect behavior of my plugin has the lowest priority. If another plugin redirects an URL, it will get the priority over my plugin.