EDraw Max program is probably the only program capable of exporting its own EDDX projects to EDX drawings which is more or less the only eddx to edx conversion that makes sense. Trial version of the program is available for download on the developers website.
Convert Edraw project to EDraw Max drawing.
We found one software available in the database for this conversion.
Microsoft Windows software - convert eddx to edx on Windows
A versatile diagramming program
Convert from eddx file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.