This is the hardest mod I've done, I'm up to 4 switches now at one sitting, takes 30+ minutes, so ~8 minutes per switch
There's only one 2mm diamond file from the Aliexpress kit fit for the job, it's surface area is flat, others are more curved - as mentioned in the comments here, getting rid of the nubs gets the job done, while you are filing the nubs, the feedback is very grindy, after the nubs are gone, the file runs smoothly - you have to push it as hard as you can, while being very steady
The process is really taxing, it's heavy on the fingers, when I first started, I was filing my thumb's nail too, currently got the hang of it tho
The process makes you philosophically dig deep into life, makes you question your choices etc. - If anyone is considering it, it might be best to wait for a truly fixed release of the switches