Don't know where you live, but where I live, they'd not be permitted to charge for repairs if the device cannot withstand what passes for normal use (e.g. uses other macbooks have no problem with). There's a reasonable expectation you're going to be able to use it like any other machine, without impaired durability, unless they've explicitly stated otherwise, and that means the machine has a defect as far as the law is concerned if this is not the case, and must be fixed free of charge. They're not doing anything they're not (here) already required to by law.
My problem is that it took 2 weeks for this to occur, and unless they have some reasonable explanation for why it happens other than "the same crap that didn't bother any of the 10 other machines you've used in the same way in the same environment messed up our keyboard", I can only expect it will happen again in about the same time. To fix the problem, I have to send them the machine and do without a computer for a couple of weeks at least.
They can keep fixing it, in which case I have the machine 50% of the time until I find some gullible buyer for it and can get a real machine, or they can let me pay a little extra to upgrade to a real machine. Looks like the 2018 models are a real machine if you don't mind extensive throttling, and I don't, really. I'll be underclocking the damn thing as soon as it comes in the door to limit the fan noise, anyway. But that's not on offer, so I can't get a machine that works.
Indelible impression, that's for sure.