Posts like this one give us workarounds (I know they're "hacky", I know they're temporary, but... they work!).
That post in particular tells us we must modify client.js -- the main entry point for Qlik Sense apps! -- (you must be careful if client.js is minified, but it can be done!)
So there are technical reasons to be careful (minification, etc), and common-sense reasons (don't change the core client.js code since a Qlik Sense update will ignore our change.), but are there legal reasons?
Are there any legal reasons that restrict our usage to edit client.js?
Can we modify our own cleint.js? Can we advise clients to modify client.js, if they accept the above risks/considerations? Will any EULA or terms&conditions prevent us from modifying, or advising to modify?