Correct, PB is not a compiler ... its a development ecosystem really when you think about it.
The PB object source is just that. It's readily available as an export / import via the IDE, OrcaScript or using native source control (my favorite way to keep automatic track of object source).
The main thing to remember is that along with the object source, PB keeps a copy of the compiled object in its PBL's as well. That's why it's always ready to run your applications right after a painter "save" operation. Something that regular compilers just can't do.
Your 100% on the money about the IDE vs Language vs Getting old. It's really Sybase's fault 1st of all trying to convince everyone that we needed a new IDE versus working on adding more .Net features to PB Classic (like WCF) plus controls, DW features, etc. SAP of course has done nothing to move the PB IDE forward during its tenure (so sad). Now we have PB.net based on an outdated VS2010 and almost obsolete.Net framework version support. What a waste of time - that could have been put into PB Classic moving it dramatically forward.
Boy, do we Appeon ASAP!