Being a relatively "long" word and being Latinate, "equilibrium" is probably more commonly used than it might seem. For example, the sentence "After a long period of change, things are finally coming back into equilibrium" would not have much feeling of formality to even a young high school student.

That being said, here are some possible expressions using the concept of equilibrium in an informal way and in the sense of describing a general state of things in response to an everyday question such as "How have you been?"

It's good to see life coming back into balance. I finally have some time for myself.
It'd be nice if everything could just even out a little bit.
Things have been topsy-turvy. I hope they will return to a steady state soon.
Last year we were up and down, but this year has brought us a period of stability.
Things are steady right now. Everything seems to be pretty much in equilibrium.

(The word "equipoise," which you might see in a standard Thesaurus is definitely a more formal, more educated, far less commonly used synonym.)

For adult speakers, in all four of the sentences above, you are just as likely to hear "equilibrium" used as any of the alternatives. "Balance" is the simplest one-for-one word exchange and would be well inside an elementary-school level vocabulary. Whereas, "equilibrium" would probably not begin to enter an average native-speaker's vocabulary until 13 or 14 years old.