Maybe it's specific to american english.
I checked cambridge dictionary and it confirms that definition : tending to support and encourage unity among different religions
Merriam-webster has a similar definition : Worldwide or general in extent, influence, or application
Also collins dictionary : interreligious or interdenominational
https://dictionary.cambridge.org/dictionary/english/ecumenic...
https://www.merriam-webster.com/dictionary/ecumenical
https://www.collinsdictionary.com/dictionary/english/ecumeni...
Link to the Frasier clip :) https://www.youtube.com/watch?v=QfrFkxDzpLU