To open the project with an older Construct version:
Change the extension of your c3p file to zip, unzip it to a folder, open .c3proj file in Notepad and edit this string:
For example, you can change it to 15200 and then try to open this project with different versions starting from release 152. Of course, this will only work if you are not using new features added in later releases.
You can also try to find what object is causing the type mismatch error and fix it manually in JSON files. Press F12 in the editor window and then try to open the project, you may see some additional information about the error in browser console log.