There are no "5-star" hotels in Jarabacoa, period. The best is the Gran Jimenoa. It is more a local/upscale Dominican mountain resort.I really don't think anyone could describe Gran Jimenoa as luxury. It's a 3 star type of place and I get the impression that it survives with groups of Dominicans coming to their Karaoke bar (I dread to think how noisy that is). It's OK, it's clean, the service is nice, but it's not luxurious.
If Villa Celeste is open, it's worth trying. Run by Vanessa, a New Yorker who previously run a cleaning company and you could literally eat your food from the floor. Really nice pool and only 8 bedrooms so it's quiet. I've stayed at both and in my view Villa Celeste is by far the better option if you're looking for boutique upscale type of places.
There are also some very very nice properties on AirBnB some of which have pools and come with full service, so it's worth a look.
We have been major patrons for 11 years and know the owners well. The GJ has been consistently upgraded J and is a fine, fine place with a solid reputation.
It does not pretend to be "boutique" but maintains consistently high standards in physical plant, food, cleanliness and customer service. It's one of the few Dominican businesses I know of who plow much of their profits back into the business.
It "survives" by being consistently packed on weekends and holidays with folks from Santiago and Santo Domingo who want to escape the city chaos and heat.
It may not fit the expectations of foreigners looking for first world excellence and "stars", but it is a place well known in the hearts of the Dominican society.