There are many sealers that can be used on cinderblock, but only one category of sealer that can be used to waterproof cinderblock. It is not secret that cinderblock will soak up, let in, and store water like a sponge.
Impregnating sealers are the best type of waterproofing sealers to use on cinderblock because they fill in the pores, regardless of size, 100% with a hydrophobic barrier. Of the impregnating sealers available, a silane/siloxane blend is by far the most effective. A benefit to using a silane/siloxane blend is that aside from sealing the cinderblock, silane/siloxanes will also seal the grout and minor cracks.
Cinderblock sucks. I tried a ton of products and nothing helped. I had to actually dig out my foundation and fill in the cinderblock with poured concrete. Not a fun project but it stopped all water issues.