I have seen real eneloops leak. They don't leak alot but it does occur at the positive terminal.
BTW I don't know if I would recommend silicone WD40, I do use it, but I had stuff rust with it on. Its just not as good as grease.
Take a piece of clear glass, spray some on, and see what happens over time.. I always meant to.
I use the silicone wd40 for things that are hard to access/annoying and I need it working with lubrication that is more trustworthy and longer lasting then regular wd40 which is kinda dodgy for protection IMO. I don't think it would be my top choice for a 'easy to access job', but you would need to do experiments, I never found the time to try to get to the bottom of lubrication.. it might be acceptable. I bet it would be OK for wafer toggle switches.. but I use deoxit spray for that. Sometimes dealing with the metal folds breaking is more annoying then using excess lubricant.
One thing I do like from wd40 is the long term corrosion inhibotor that smells like mothballs.. well you can mothball something with that. I sprayed it on stuff I just don't have the energy to protect otherwise, and its in surprisingly good condition after being left in un regulated nearly outdoor conditions for long periods of time. I guess its cosmoline spray. But it gets really tacky and eventually dries up like wax or something. But better then having to clean a bunch of flat bars from rust 2 years later after throwing them under a awning. Clean it off with a rag of fresh regular WD40 from the bottle or cheap solvent of choice before use. Kind of expensive but it prevented some rage IMO.
And I don't know what silicone without dielectric properties is. Maybe it means that its more pure. Some electrical greases have like silicone dioxide in them for some reason, I don't know why. I assume its incredibly fine powder. But all silicone is very dielectric. When they give it a dielectric grade, it might be related to high voltage behavior. Perhaps some grades have a lower dielectric constant, (worse at arc prevention). Unless its another reason, I don't think you need to worry about that with batteries unless its in a electric car or something (like a passanger car). Or it might have to do with the consistency, i.e. for the 'grease packing' application I mentioned, you might need a assurance for code reasons that the grease will not flow out of the enclosure and stay in the same place for 20 years to make a ingress seal. Perhaps they add some stuff to it to make it more thick.