mod and prj files were last used as the default output in Monarch v6, a decade ago. Monarch v8 could only save xprj and xmod files. If you've got an xmod converted, then the project should be easy to define. You just need to work out what the input filename(s) were, and what exports were defined. Most models just open one file, and tend to have one export defined. The export could be the report (rarely), the table (possibly with a sort and filter applied), or a summary. If you open the prj file in notepad, you should be able to see what was the oiriginal intention, and then just open Monarch 11, load the input file, the model, define the relevant project export and save the xprj.