Overall you don't need certification to be a sniper on fields, there is little benefit to running a 450fps+ rifle anyways, so you can go with a bolt action under 450fps and have a blast without certification. Case in point, I ran my M24 at around 500fps for many years, and the final couple years of playing, I had much better accuracy and success (and fun) with it set at 395fps (0.20g) and launching 0.36g Bastards at ~300fps....... anyone can do that, is all a matter of learning to shoot, watching the BB flight path, adjusting as needed, all real steel skills.
Certification itself is really only a means of 'certifying' that you understand minimum engagement distances, safety issues, and such. Really it's just about being safe. What courses DO as a benefit is spoon feed you a massive pile of skills and learning in a short period of time to make being an airsoft sniper for fun for you, shooting, movement, etc. with less frustration.
Don't treat it as a requirement, and don't think higher powered guns give you an advantage, they really don't make that big of a difference.