Boundary Markers of European Airspace
No, your assumption is not correct. Airspace boundaries are not defined by waypoints, but by WGS84 lat/lon pairs, which you can probably just use directly without a lot of manual work.

You need to consult the national Aeronautical Information Publication (AIP) for the country in question to get the coordinates for their national airspace, called a Flight Information Region (FIR). Specifically, look in AIP section ENR 2.1 (all AIPs worldwide are structed in the same way). Here is an example for the UK: https://www.aurora.nats.co.uk/htmlAIP/Publications/2020-03-26-AIRAC/html/eAIP/EG-ENR-2.1-en-GB.html#ENR-2.1

I recall having downloaded a global file with FIR coordinates for the entire world somewhere off the web, although I don't remember exactly where. It may well have been published by the ICAO. You might be able to locate it if you look around a bit.