My thoughts would be she is back in 'pack' mode again, remember she was an abandoned dog in Crete, probably ran in a pack, large or small, but lived as a wild dog obeying purely dog instinct, being in kennels, what happens there? Dogs howl, bark, constantly, she's only doing what she has just learnt to do in her opinion to survive, the barking, howling brought food and people, it is a mimicked behaviour, and also a way for all the dogs to bond in their sadness and upset at being in kennels, along with calling for their owners, give her time to get used to home again, might take up to 2 weeks, and IMO if you go away again, I would use a dog sitting service where she can go to a home to be cared for living as with yourself, without dogs howling and barking to set her back again.
Some dogs are fine in kennels, some are very unsettled for a while when coming back........ in 2 weeks she will hopefully be back to normal.