Standing comes before talking. You're right that since he can stand, he is, in English-speaking terms, a toddler. I have no idea if Japanese makes that distinction. But a toddler can usually stand and walk months before first words, and expressing complete thoughts can be a year away still at that point.
I'm assuming he is somewhere between 12 and 18 months, at most.
Those maids need to be fired. They are terrible at their job. Or maybe that's what the nobles wants... irresponsible maids that look the other way whenever the emperor is outside. lol