Do flowers keep for a little longer if they're frozen?

Probably not, unless their cells have an infinitesimal amount of or no water.

From what I’ve seen, florists usually keep flowers in chillers with abundant air circulation.

So the fridge?

I think so.

I would suggest placing your flowers near the center of the top shelf or the first one below it, with maximum surrounding space.

If I’m not mistaken, your fridgey has an air distributor in the back and above the top shelf, so try to minimize any obstruction between the flowers and the distribution register.

That should provide optimal air circulation.

When a frost hits unexpectedly, flowers die even though they aren’t even cut. Don’t freeze them.

When things freeze, tiny ice crystals form inside the cells, that perforate the cell walls, and destroy the cell.
Most living things are incapable of surviving being frozen.
I would wager that to include flowers.

@Brian1946

“I think so.
I would suggest placing your flowers near the center of the top shelf or the first one below it, with maximum surrounding space.”

^

Most likely wrong.

Per Google:

Fresh Flowers & Roses should not be placed in either the refrigerator or the freezer! ... The Freezer is simply too cold! When fresh flowers & roses are kept at freezing temperatures even for a very short period of time it can result in the discoloration of the flower & premature death.

https://www.flowerpatch.com/flower-care-styling/

Would you believe that I got my Botany degree from tRump U? Well, at least I can say they gave me a BS degree. ;-)

Well, I asked the florist who donated them. She said just put them in water. The event is tomorrow so they should be OK for that long.

Keep them cool if you can, but not frozen. Even fridge is too cold. Do you have a basement that’s cool? You could keep them there overnight, but bring them back into the light in the morning.

Disclaimer: I’m not any sort of expert.