It seems the only capable of EC4 to PRINTCD2 conversion is the Epson Print CD software from which both of these file types originate. Probably no other software can perform this conversion.
Convert EPSON Print CD document to Epson Print CD file.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert ec4 to printcd2 on Windows
A program for creating labels for CD/DVDs
Convert from ec4 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.