Maybe this will help:
starting caladium bulbs indoors

First of all, caladiums are like DLs in that there are early, mid and late blooming and the whites are typically later than then reds. So don't give up on the ones that haven't sprouted. If they feel solid, they are still very much OK. If I were you I would pot outside and water sparingly. At this point you have nothing to lose and much to gain. I'm assuming you are pretty close to the end of frost date for your area. If not, maybe you can pot them all quickly in a large pot or pots and keep them growing indoors and watering til its safe to take outdoors. Good luck.

My last frost date is in about 2 weeks.

These were all to be potted into mixed annual containers. I
have not bought the annuals yet; I normally do a big purchase out of state at the
end of May. I’m afraid they will be dead
if I wait til then.

If I understand you correctly, you are saying I should pot
them up. If I am going to use these how I normally do, that would be temporary,
though. If I pot them in clusters ( I wouldn’t have enough space to plant one
or even 3 in one small pot), how well do they handle being separated when
planting out into their final pot destination? Thanks again.

I don't think they resent being moved at all. I believe it'd be OK to pot them up now and them move and rearrange as you want later on.

One of the major caladium growers says remove from packing at once, so I think ypu were right to remove. I think the peat moss should have been moist when the shoots started growing.