In case you still have e3 system for your old embroidery machine, this workaround can help you to manage the version of EMB files well.
1) in Design Library, select all of those e4 EMB files.
2) then click on the Convert button. Please see the screenshot below.
Therefore, instead of saving each individual design file into e3 EMB file during digitizing, you may change the digitizing workflow as following.
1) you digitize designs in e4 software and save design files to e4 EMB files as usual.
2) at the end of day, you do a EMB file version batch converting to the e3 version of EMB files to a different folder.