I agree with you that there should be an official adding of venues simple list. (There are posts, that show how to add it.
There are different possibilities to use google maps, please try all (see helppage in JEM), even in venue part.
(Please before asking always try to read the help first.)
Testing JEM 2.3.0 beta3 local on clean latest Joomla (3.9.11) Protostar php7.3.8 (no mails)