My name is Daniel, and I’m evaluating Invoiceninja to change our software to this solution. We have installed a self-hosted version and created a template. For RGPD compliance, all pages of all invoices must have the data of the business (CIF/NIF, social name, telephone, address, etc.) in the left margin of the invoice. I attach an example. Is like a text rotated 90º, and going from rear to top of every page. We have been looking for information in this forum and in PDF Make to do this, but no luck.
I have no idea if this is possible in the invoice design editor via adding text directly, but you might try creating an image with the required information on the left-side (and blank everywhere else) and importing that as a background image.