I guess the one reassuring thing is - the smaller batteries don't appear to have enough in them to do enough irreversible damage (only seems to corrode the contacts, which people are able to resurrect with some scouring or sanding), while the bigger ones do indeed leak out a lot more, the acid doesn't appear to do much initial damage to the plastic (could weaken it for the long term though) and unless the electronics are gravitationally below the batteries (or a hole or gap in the battery compartment) usually only the contacts will be damaged, which may well be resurrected as well with a bit of sanding.

See the photos in the first post - the examples I gave show that the corrosion was limited to the contacts (Supreme Cheetor, Armada Jetfire gun), and where it was a complete acid leakage, it ran down out of the battery compartment away from the actual electronics (Armada Superpants Prime).

The worrying thing though is that just about all the new moulds since 2006, have the bigger batteries now, not the small button cells... which is more prone to big leakage. Since they are (cheap) Hasbro-brand batteries, they might be worse, or maybe a type they've specifically created so that it doesn't leak. It might be too early to tell though, as it was more than 5 years before notable leaking occurred in my toys.