Google's systems were designed to index mountains of low value data at hitherto unseen scale, and they're good at that. But, to-the-second system-wide precision with full audit trails ... not so much.

You keep seeing startups with ex-Googlers that think they can "disrupt" Fintech with Google's "secret sauce" ... this tends to go badly.

I've had to clean up one of these messes where, in all seriousness, even a pre-2000 LAMP stack (never mind Java) implemented by people who understood the finance domain would have worked better.