It is difficult to say. We don't yet have a way of telling whether or not time is passing in our worlds as we are here, and if it is, at what rate. While the calendar system of Lunatia is similar to my own, space has a way of distorting time.

But with luck, we will be able to return at the same time that we left. After all, some people have arrived from different periods of time entirely, if the case of your acquaintance.

[The situation is definitely not as pressing for Colress, but he would like to have not missed out on all that time to work on his research...]

But it is good to know that you will have support, at the very least. I would try to focus on that knowledge, should the true scenario of time passage turn out to be less than desirable.