I am still not clear on what you want.
If you look here, you will find some idea of how to find the tach crossing times. You may need to change it to find both positive and negative crossing locations.
If that is what you want then you are done.
If you want the rise time and the fall time, then once you have these locations, you can just go backwards one point at a time until the slope changes and then forwards one point at a time until the slope changes. Then you will have the rise and fall times.
With the signal oscillating at the maximum and minimum values, it is not clear what you want for these values, but once you have the tach crossing locations you can figure that out.