Template generators are very useful. if you have an existing pdf, you can create an interface for pdf generation surprisingly fast. Highly recommended if you want to manage your templates on a pdf basis. Loading Japanese fonts was also smooth. Also, pdf-lib is used internally.
labelmake is one of the more interesting libraries that I have recently tried out. I tried it out to generating PDF files containing barcodes for products in an e-commerce website. From my personal experience I would say that it's a nice little module for generating PDFs however, the documentation is seemed a bit lacking to me. Also, there are quite a few nice alternatives available out there which might be worth checking out.