Would love to have a tool like this that worked for making new invoices, among other things!
Most likely, the PDF used a subsetted embedded bold font, so it only worked for letters that happened to be present in the original text; any new letters were missing from the font and you got a fallback.
Just one of many reasons why a tool like this is the wrong way to approach pretty much any document creation/editing task, because PDF is the wrong document format to use for these purposes.
Wow, that seems to be exactly right, based on which letters were bold and which weren't. Very interesting!
To the folks downthread who asked about the legality of modifying invoices, I was trying to use one invoice as a template for a second invoice. Most things are the same, so it would have been great if I could have made a simple change!
Not the same in US?
I don't think laws are ever that prescriptive about what you have to do. As far as I know, the only requirement is when the tax inspector arrives, you need to be able to produce a complete and accurate list of all invoices you have ever sent to customers.
The Finnish VAT Act does, however, require that companies sending and receiving invoices ensure that the mandatory invoice data is not modified after issuance (209 g §).