Does a center channel have to match the front spke

You would be better off with matching center channel speaker. Their will be things that will pass from left to right or right to left and will travel thru the center speaker. If they do not match fairly close, you will hear the tone change as it sound leaves the outside speaker, passes thru the center channel, then change back as it enters back thru the opposite outside speaker. Of course, if you find a dealer that will let you demo a non matching center speaker, try it and see. You just might get lucky!

the center may not have to be an exact match for your mains, but you're better off if it's a close match. If Dynaudio has a budget center - not necessarily the same speaker elements but having the "house sound" it will probably work. When I first started to assemble my HT, I tried a couple of center speakers that were decent, but not the same brand - it was awful. I now use the entry model center speaker in the same brand as my mains (which aren't entry) and it works nicely.

Good question!
For proper film, center is for dialogue only-so that leads one to believe you could use a different speaker successfully. Music/effects are NOT sent to the center. However, there are some newer mixes that defy this and who knows what future mixers might do? So this sort of says "the only safe bet for the future" is all speakers the same. In my own case, I cannot do the same so I use (the same brand center) that is voiced the same as my L/R/SR/SL. Less low end in it (fine for dialogue) but sounds very much like the mains. I spent more than I thought I would for the center but all other lesser options sounded too different. I am glad I did, sounds really nice now.

For music, different story completely. Music mixers DO use the center for music, they can sort of do anything they want, so this means all speakers must be the same, rear channels, center, fronts.
Brad