Until now, I've never experienced any problems of using an older client version of Oracle with a newer Server Oracle version, as long as you don't use anything that wasn't supported in the "older" version. Oracle seems to be quite backwards compatible.
No guarantees, but ... why don't you just try? Maybe that's not possible right now for you, so sorry for my ignorance :)
No don't worry. If it was me reading the question, I would also see it like you understood it.
Note: Using a mismatched client version compared to the DBMS Server is not recommended by either Oracle (or any DBMS vendor for that matter) or Appeon. So basically ... you would be "on your own support wise" (aka "use at own risk").
Regards ... Chris
Our DBA gave me the attachment I now added on my question. They say if I read the image right. that it is fine. I just don't know about Powerbuilder.
Its not related to PB as all MW-Windows Apps that call the Oracle Client are at the execution & stability of that Oracle client version compared to the Oracle server version that they are talking to through that client. As I said before ... "Use at own risk". So if your DBA is forcing you to use a different client - then test, test, test ... etc. That is the only way to trust this mismatched software in any App IMHO.