EN287
Sorry for the late reply. In the USA, there is no official national "License" scheme for welding. Many jurisdictions have license requirements, but not all of those are related to a demonstration of ability or qualification. Some are only for revenue raising.
There are some voluntary welder qualification and certification schemes that are recognized extensively, such as AWS D1.1, ASME Section 9, API 1104. Many of these "Certifications" are legal requirements, because they are incorporated by reference into building, plumbing, boiler, and other "Codes" of the jurisdiction responsible for the code.
By jurisdiction,I mean State and Local governments, Cities, Counties and towns, as well as "Authorities" (Quasi governmental entities with the power to operate as a legal body).
The requirements for obtaining one of these "certifications" mostly follow the cited Nationally recognized code, such as ASMESection 9, or AWS D1.1, ETC. Until recently, New York City had a welding license requirement for structural work. While that license requirement was in force, the time delays to get a test date and then to wait for the results, were unreasonable. The actual test was essentially a modified D 1.1 unlimited plate welder qualification test, (There were actually more NYC pistol licenses given out, than NYC welder licenses!)
I doubt that any of your EN licenses would be valid in the US for most work. I have done commonality comparison reviews of various EN welding related Norms, and was never able to find enough common ground with US Codes and recommended practices, to unconditionally accept an EN license.
Costs of licensing vary depending on the jurisdiction. Licenses issued by one jurisdiction, even though obtained by the same qualification test, usually are not recognized by other jurisdictions. Even non-license type welder qualification certifications issued for ASME work by one contractor on a project, (I.E. a large power plant) cannot be transferred if you go to work with another contractor on the same project!
There are some unions that have programs that make welder qualifications transportable, such as the "Common Arc" program. Many building contractors will accept some city licenses or State DOT licenses as qualification to weld on their project. Although this is often done, it is seldom completely legal.
Canada has a national licensing scheme for various types of welding work.
Joe Kane