What are the acceptance rates at various CS masters degree programs?
I suspect that most programs do not post their acceptance rates at the master's level. That's in part because they could be subject to wild fluctuations from year to year, as the number of applications change.

In particular, one other thing to consider: most graduate programs have a target of incoming students they want to enroll. They will generally admit only as many students as they feel they need to reach the goal. If students are accepting offers at higher-than-expected rates, they may lower the admit rate in subsequent years to compensate. Similarly, if they are under their target, they may admit a larger than expected pool.

Considering top-tier schools, my suspicion (although I don't have the numerical evidence) is that they get enough qualified applications that admissions now are partly a "lottery": if you meet the qualifications of a typical student, you may or may not get in, depending on the needs of the department in that particular year. So just do your best.