The RP is set in modern day, yes. But given the secrecy of magic it's very, very unlikely they'd be made for World War 2, and especially not on a mass scale. Since they're replicas of human life that require a soul in order to function, getting that soul is the reason they are purpose-built rather than built on a large scale. That and the assembly of raw materials for the body often proving to be a somewhat complex process that requires care. They also don't usually come with expiration dates, as homunculi are built to freeze at either an optimum age for their purpose, or just to freeze at some age where they will function well, and then cease all aging. If a homunculus does die like that, something was done wrong.

And we already have our single homunculus, as well. ^^; Since, while they're not super-rare given how useful it is to have a purpose-built person who has been "programmed" for loyalty and can be "programmed" do do all kinds of things a human cannot, they're not common enough that more then one would be in a single small agency like this, unless Toshiko was actively seeking them out.