Good news!
Bulk pdf generation for Tapestry learning journals is now generally available.

Go to Control Panel > Manage Children

then tick the children you want to generate PDFs for.
A popup should appear on the bottom right of the screen starting
"With X children Export...",
Click on the "Export" button on that popup and choose "Export Journals as PDFs",
then click "Go".

As this is likely to be a very popular new feature, it would be wise not to leave it until the
last day of term and then try to generate 50 journals!