Seeing this from a users perspective, it seems this XML invoice approach is being pushed down from government in many countries and it seems this is not a question of IT or businesses being ready as such, as this seems to be somewhat political. Reason being this is more convenient for governments and cost effective or for tax surveillance etc. So this XML thing is basicly falling into Manager user’s lap to solve whether we like it or not.
In my country, Iceland, this government XML adoption has been postponed year after year but now in 2020 the government will not accept bills on paper or PDF any more, so XML invoices is the way to go. This is not a problem for the big companies as such as they use software like Nav, SAP etc and this has been programmed into their software but these larger companies have been using XML invoices B2B for a quite long time with good experience it seems. But for smaller companies this is something they are not prepared for.
As a short term solution, and not having to manually type invoices, I agree with @Roberts, regarding if it is possible to take small steps in changes in Manager if it can help users with some manual batch mapping or making the steps fewer in some manual process to produce XML invoices.
I must admit that at first I fell into the pitfall of thinking this is just some simple XML export of some mapping after seeing a XML textfile as these textfiles look rather simple. But after talking to XML experts there are all sorts of small errors which can start to creep up if you are not careful. These small errors demonstrate the complexity of this standardized mapping and this is likely what @Tut was talking about.
For example in my country there is nothing called “unit” like if you sell a couple of units from stock. The XML standardization must be some specific code from United Nations standardization list which says what is exactly being sold, that is “unit”!.
Another example is how to tackle standardization of which currency is used which I gather can also complicate things.
Then also validation of XML is not always enough, if the receiver of the XML bill has to have some special id, which he provides, on the bill for it to be acknowledged, otherwise the bill is discarded.
Sometimes there has also to be not only billing address but also a standardized cost address, like a big company wants to know in which of their branches the cost occurred.
So from all of these examples above and experience of talking to XML experts how XML invoicing has been done locally, it seems that to have this XML mapping automatic and running 100% correct it must be locally programmed/mapped into the accounting software, based on local legal detailed standardization rules and other needs of businesses.
As a long term solution for Manager, which likely only @lubos can answer, mapping to standardized XML would maybe be possible for local programmers to solve, as they seem to be good at this XML mapping, when Manager’s plugins will be available ?