How is it a challenge order? Do you have to pay regardless? Do you get the money back if you win? What are the rules?
The point of the challenge was that it was so expensive no one would even bother
trying to challenge it. It was not really meant to be feasible
as a challenge, just something the owner could put to save her damaged pride. It's why her very last challenge literally put
everything in her inventory into the single bowl despite how stupid that is as a business decision: so what if the person failed the challenge, you just put your entire inventory of ingredients to waste on top of all the other debt you accrued. It's why the final blurb said she'll be in debt for the next decade: she may be a good cook, but she's an
awful business owner.
Maybe? The volume extra doesn't show her locking eyes with Rentarou, we never see her do so this chapter, and it
could be justified that she was so focused on Kurumi as the challenger she barely acknowledged Rentarou's existence this chapter. Granted, if she
does return she's gonna be in monumental debt and probably nursing a grudge blaming the family for "ruining" her business... even though it was her own spiteful nature and horrible business acumen that was responsible.