( I’ve moved this to projects so you can get answers specific to your own set up. )
Welcome! You might be able to do this, it’s going to depend in part on how precise the timing has to be for the multiple toggles.
There have been some people in the past who’ve been successful in setting up a relay as you describe to disable the motion sensing on an outdoor light switch that acquired a specific toggle pattern in a short period of time.
much depends on how precise the timing has to be
However, I don’t know if that is still working. Since that was done, a previously usable smart app, “double tap,” which was intended to capture multiple taps on the physical switch, stopped working because the cloud processing became inconsistent in how much time it took to process the taps and it became very hard to recognize the specific double tap pattern.
I understand your project is different, because you want to just send the multiple on/offs to the switch, not toggle at the switch , but I did just want to mention the double tap issue because it’s been a change in the last few months.
So I think yours is worth a try, but if it turns out to work sometimes and not others, the issue is probably the cloud timing. It might also work better for taps lower in the sequence, like one, two, or three and turn out not to work very well for 11 and 12. Again, that’s just something you have to try and see.
related ideas
So here’s the link to the on/off pattern project I mentioned. You’ll see that I thought it wouldn’t work when it was first brought up, but @tgauchat , one of the grandmaster coders in the community, wrote some code that did work for that person, so I definitely think it’s worth a try. 
( I’m always happy to be wrong in situations like this where the person ends up with a practical solution that works for them . )
Oh, and if you haven’t used custom code in SmartThings before, it’s pretty straightforward. Basically you copy someone else’s code and paste it into your account. Here’s the overview FAQ for how that works.