The noun brainchild is used to refer to a product of one’s creative work or thought (the child of one’s brain, of course!). This heady compound is used of events, campaigns, companies, or elaborate projects—or the animating idea behind them. Use of this term usually connotes a degree of admiration for something truly original, and is almost always used in the context of giving credit or attributing success to a certain creative individual. So where there is a brainchild, there is usually a "brain parent" mentioned nearby.
Adapt and accommodate both mean to adjust or modify, or to make suitable to requirements or conditions. For instance, you might say you've adapted your behavior to a new country by learning the language and customs. You might also say you've accommodated yourself to your new country by learning the language and customs. The key difference here is that the direct object for adapt cannot be a person, while for accommodate, it can be a person as well as an inanimate object. Thus, no matter how much one may want to, one cannot adapt other people, but one can accommodate them, which may also mean one can host or take care of them.
To be jubilant is to show great joy or triumph. Contrasted with the word happy, which conveys delight but not necessarily to a high (or noisy) degree, jubilant shouts its elation from the rooftops. It comes from the Latin verb jūbilāre meaning "to shout, whoop," and fittingly, you're most likely to find it describing the mood or manner of people gathered in celebration, or with something to "whoop" about, as a success or victory.