Actually, it seems that google is now able to cope with things a bit better. I've just tried and I can now ask for "how long left on my 45-minute timer?" and it does finally answer. It actually also shows up in the UI. That is sort of recent, though, as I've had that problem earlier this year. It seems that siri is now unable to set multiple timers, though.

Anyway, it does seem to have improved, but I wonder why that stuff wasn't in from day one. It seems pretty obvious to me.