Joscho’s use of swiping is not a mistake since there is no possible way it can be “fixed”. USX motion cannot do downstroke string changes with alternate picking. So Joscho’s solution is more like a trick or a hack to enable a lick which is not usually possible in his picking style. Not only that, but it takes skill to perform it sonically invisibly, and he does it perfectly every time. In any practical way you can think of, what Joscho is doing fits what we usually think of as a technique.
All that being said, it sounds like you’re hung up on what things are called, and whether they are called something good or bad, or mistake or technique. That type of thinking is not helpful, as @Pepepicks66 is pointing out. These are just language questions that end up being limiting beliefs.
If you want to stop worrying about these things, the best way is to play awesome things that you think sound great and make you excited. This will put you in a positive hands-on creative mindset where you play and enjoy.
The best way to do that is the checklist I’ve posted above. Where are you in that checklist? What problems are you experiencing? Post a clip if possible and we will get you over the hump.