I've been in fiber for 14 years now, since I got out of highschool. I had a small background in coax before that working for my stepdad as a coax splicer. In all of my 14 years, I have only heard of certifications for fiber related work, in a joking manner. They arent required, nor needed. If anything, youre going to be looked down upon just mentioning you went to so-so school...as you will need to un-learn most of everything they taught you.
As Mentioned above, real fiber splicers that can read/understand an OTDR, troubleshoot quickly and also work in hot cases without a ticket and maintain no outages...are far and few between. It's almost pushing me back into the field versus the position I have taken as a Sup because the demand for quality is so high and the supply is so short. Tons of guys can put fiber together, most cut corners during prep work, can barely run a bucket and pretend to know how to troubleshoot anything...and In reality, none of it is that hard...at all.
FOA course's(Which I have taught as a certified instructor before) are good for background information, fiber theory and the in's/out's of different applications but none of that matters in the field. I once had a guy pay me to FOA certify all of his crews in fiber, we did 3 FOA courses, it took about a week total per group. He wanted it to look good on paper when he was trying to gain more work in the future, and I had no problem teaching it. They understood the basics of splicing but in reality the on-the-job training meant so much more. Book knowledge isnt going to get you anywhere when you are knee deep into an outage and the maps for the plant you have are outdated by 10 years. if they were ever correct to begin with.
Find someone that knows what they are doing, ask around, and see if they will allow you to shadow them. Chances are, most people wont, but some of us dont mind.
IF you want to know if they are a good splicer or not, Ask them if what their favorite cleaver is. IF they dont have one..move on. If they cant name more than one, or tell you some bad ones...move on.