On ./static/src/js/multiprint.js, line :24 there is a call to

self.connection.rpc('/hw_proxy/print_xml_receipt',{receipt: r},{timeout: 5000})

Is there a way to force the creation of a pdf instead? Better if a qweb report formatted in Odoo and reprintable trough the report_to_printer module...

Summarizing, grab the temporary table of the pos order without the needing of close it and create a pdf on the fly. This will solve many issues with not compatible thermal printers!