Why not הכריכים הם טעימים?
Because טעימים is an adjective. You only use the copula for noun is/are noun sentences.
Someone answer this question!
One of the 3 options I had to choose from was חיות מחמד טעימים "pets are tasty" lol
How is כריכים pronounced? And could one also say סנדויצים?
Krichím, you can hear it yourself in the recording here. And yes, one can definitely use סנדוויצ'ים, it's even more common.
I wrote : with הם !!!!
because in nearly the same sentence just before it was called MISTAKE to say ist without the personal pronoun. Who can explain this please !!!
....הכריכים הם טעימים
You need the copula for "[noun] is [noun]" sentences. You don't need it for "[noun] is [adjective]" sentences.
So in your sentence הם is not needed but it is correct and should be accepted, as far as I know.