This TypeScript library simply provides one JavaScript class 'EpsgNumber' with lots of EPSG constants.
Those constants can be used for getting intellisense help, for example when using Visual Studio Code.
When the class was generated, the EPSG dataset version 10.011 was used.
Those EPSG version numbers (10.11) are also used for the major/minor numbers of this npm package (with version 10.11.1).
(the last part, the so called patch number i.e. "1" in "10.11.1" is only for this JavaScript/TypeScript library i.e. not related to the EPSG dataset version)
Regarding the data itself: Ownership of the EPSG Dataset by IOGP is acknowledged as in the Terms of Use
Some quotes from the above linked webpage 'Terms of use':
"... The EPSG Facilities are published by IOGP at no charge.
Distribution for profit is forbidden ...
Ownership of the EPSG Dataset by IOGP must be acknowledged ... "