The AdobeViewer dictionary problem you mention was one (of several) reasons I removed v15.3 from my PB360.
AdobeViewer and pdfviewer work OK on v15.2 - they're not error-free (none of the many PB firmware attempts are) but they are useable.
Another option, if you still have the hacked version of AdobeViewerv15.2 on your PB360 (for epub custom fonts). Try also adding the .app name you gave it (in the system/bin dir) to the PDF line in the
/system/config/extensions.cfg file, e.g
Code:
pdf:@PDF_file:1:HackedADE.app,pdfviewer.app,AdobeViewer.app:ICON_PDF
That should also allow you to use the hacked AdobeViewerv15.2 to read PDFs on a v15.3 PB360. I haven't tried it, but it should work. As far as I know the hack didn't touch any PDF functionality.