To be able to read the CD-RWs made by DirectCD the other PCs (with the unrecognising CD-ROM drives) may need a UDF VOLUME READER click here. Also it'll work on "some MultiRead CD-ROM drives" only.
"UDF VOLUME READER
Enables some MultiRead CD-ROM drives to read UDF formatted CD-RW discs (such as those written with DirectCD) under Windows 95, 98 and 98 SE, Windows NT 4.0 SP3 or higher and Windows 2000/XP.
Once installed, you do not need to take any special steps to activate the UDF Reader; it is constantly active in the background, waiting for you to mount a UDF disc. This is a free download for the convenience of users who do not own Easy CD Creator."
"...at worst does not recognise that a CD-RW has been inserted" - a standard CD-ROM drive (Non-CDR/RW drive) cannot be expected to behave like a CDR/RW drive, but with the UDF volume reader installed should be able to read files & folders of DirectCD-created CDR/RWs just like they were standard CD/discs.
"Is DirectCD unreliable?" - DirectCD isn't itself unreliable but the way in which it 'packet writes' data to a disc is. From my own experience the data doesn't remain for long &/or I get 'data loss' warnings quite often. You'd be better off writing the CDRW the normal way while choosing to make it a 'multisession' disc so more data can be added (or deleted) from it at another session/time. You have to try it to see if this multisession-created disc suits your needs.
Your copy of Easy CD Creator (ECDC) seems outdated. What is the version you're using? Try to get an update or a newer version. The update &/or newer versions of ECDC should give you less hassle with long file/folder names.
Hope this helps. G