I just looked up the minicart thing, and found that
a) the minicart in Tiki Wiki is version 2.5.0, which is two years older than the last version Jeff Harrell published (last is 3.0.6 at https://github.com/jeffharrell/minicart/commit/963129ff47927ade14886755f793a96bad859f8c) and even that is
b) unsupported by Jeff Harrell since 2015...
Tiki 21+ uses the last version (3.0.6) and that works fine. I've just updated one of our shopping sites here to add international shipping with a tracker, a plugin
Oh, and please do improve the documentation where you see it isn't good enough rather than just complain about it - as you know, Tiki relies on volunteers to help!