I think you're correct, but the formula doesn't appear to be doing what it says it is. Here's a level 3 sneak attack.
![[Linked Image]](https://cdn.discordapp.com/attachments/543653504619905034/764272950949707806/unknown.png)
I think (Level) in the formula is actually describing the number it's next to, as your 2 in your formula is a 3 for me at level 3. If so, the formula is scaling correctly.
However, this is still incorrect compaired to 5e, as it's multiplying a 1d6 result instead of rolling additional dice.