I've downloaded the latest version of Movavi Video Editor and created a sample project. I've saved that project and checked the output file format. It turns out that Movavi Video Editor saves its projects as MEPB file format. Therefore, if version 6.3.0 saves the projects as this format, you will be able to import them into the new application.
Also, the version I've tested is 14.2.0. I've looked for 6.3.0 and 9.0.0 but couldn't find the downloads to install it.