Best approach for this setting

Perhaps another approach is to keep

enableSemantics( sandbox.semantic-mediawiki.org );

but to also add the following:

$smwgNamespace = 'https://sandbox.semantic-mediawiki.org/wiki/';

I am not sure what the recommended approach will be. I would still prefer keeping the $smwgNamespace setting out of it since I think it has a different scope and rather have something that dectects the protocol for use in enableSemantics

[[kgh]] (talk)

So back to

enableSemantics( sandbox.semantic-mediawiki.org );

according to this comment since enableSemantics is a reference key which should remain unchanged at any time after the first setup.

[[kgh]] (talk)