You don't have to use a counterfeit charger with your after-market usb-c to magsafe-2 cable. I use it with a newer real apple charger with usb-c (... since this is an older magsafe-2 macbook, not a new magsafe-3 one, and I don't want to buy any more magsafe-2 non-detachable-cable chargers). The only downside is that it's a bit dumb and always tells the laptop it has 60W, so you need to use >= 60W usb-c charger, and your laptop will only use 60W of it.

That first link describing how magsafe 1/2 work is what convinced me it should be fine :)