[John McEnroe video] in lieu of actual substance.
This represents your confirmation bias. You read into this what you want to read into it. I found and showed the Latin here. This expression "casus si impediat" does not refer to some kind of "accident" but is actually quite vivid. "Casus" literally connotes something falling in front of you, like dropping in your path, and the verb "impedire" has the Latin word for "foot" as a root, so taken together "casus si impediat" has the image of you walking along to your destination and then something suddenly falls down at your feet to trip you up and you stumble on your way. It's very clear imagery. And this merely says that your proper disposition will allow you to get past this impediment, i.e. that it might cause you to stumble, but God will reach down His Hand to help you regain your balance and keep going, on your path to grace and righteousness.
There's nothing here about actually being stopped short of your destination, but just encountering a stumbling block that might [otherwise] prevent you from reaching your destination. You're walking along to your destination. Something drops down at your feet. You trip and start to stumble, at risk of faceplanting, and not making it. But God rewards your effort by reaching down and helping you get your balance so that you could continue on to your destination, that of grace and righteousness.
There's nothing here anywhere about death, and nothing that comes close to saying, "If you die before having a chance to receive the Sacrament of Baptism, you can be saved by your desire." Trent COULD have just come out and clearly said it. These weren't stupid men. If they wanted to teach BoD, they could have done so here. There was no need for some metaphorical pictureseque circuмlocution and use of the term "grace and righteousness". These men knew the word for salvation and could have used it here. They knew the word for death and could have used it here. They could have just said, "If you die before having received the Sacrament of Baptism, you can be saved by your intention to receive it." They didn't. Because they were leaving it open and leaving it a mystery. The ONLY thing they were saying in this passage is that, unlike in the case of infants, it's OK and even preferable to delay Baptism in adults, because for adults, God will take are of them on account of their proper dispositions to receive the Sacrament. How? One answer is that of St. Fulgentius, that God would keep them alive until they receive the Sacrament. I also pointed out the subjunctive voice here, where this obstacle/event MIGHT prevent them from getting to their destination.
Let's take this scenario. Someone had an actual serious accident and is dying. God keeps him alive until a priest shows up, with seconds to spare, and gives him emergency Baptism. And then he dies. Does this not also qualify for the scenario described by the Catechism? Of course it does. This too is a case of God bringing the soul to grace and righteousness despite some mishap that got in the way of his (planned) reception of Baptism. This type of scenario also fulfills what the authors of the Catechism had in mind. So as to HOW God would ensure this, the Catechism is silent, when, as I said above, they could very easily have said, "If a properly-disposed adult dies before receiving the Sacrament, he can be saved by his intention to receive it." You try to make these into stupid men who wrote this Catechism.
For those of you who doesn't read/understand Latin fluently, you're relying on some third-rate crappy translation. And third-rate crappy translators abound. I worked as Staff Editor at The Catholic University of America for their Fathers of the Church translation series for a few years, where I had to edit translations of the Fathers. There was one translation that I basically wrote myself because it was so bad that it wasn't even salvageable. If you saw the edits on each page, it was a sea of red.