I don't think your kitty has hepatic lipidosis (HL). Your vet would have told you if she did, since that's a life threatening condition. Your kitty is also still eating, and HL occurs in cats who are not eating.
My oldest girl has many of the same health problems your kitty has, and it sounds like you're addressing all her issues with the proper meds and fluids.
I agree with you - the Hepato support probably just tastes awful, if the only time she's vomiting is when you try to give it to her.
Elevated liver enzymes can be caused by many things - sometimes it takes awhile to pinpoint exactly what the problem is. A liver biopsy is sometimes indicated in cases where several of the enzymes are extremely elevated for long periods of time. Keep in mind that liver values (the measure of the enzymes) change slowly, so doing bloodwork often is not a good idea. When testing for liver enzymes, do bloodwork no closer together than every 7 weeks. It's great that your vet thinks the vitamins will do the trick for your cat.
A suggestion: B vitamins come in liquid form for injections. They are sold as B-Complex or you can get a bottle of just B-12. Your vet should be able to order these for you. They're very reasonable, no more than $10US per bottle and they last a long time. Since you are giving your cat sub-Q fluids, you can administer the vitamins via a needle syringe right into the line along with the fluids. You just need to use a line with an injection port. This way you don't have to make your poor kitty miserable trying to get bad-tasting stuff down her throat, and you don't have to stick her with a needle either. Your vet can tell you the proper dosage and show you how to draw up the liquid into the syringe.
Hope your kitty feels better soon. Please let us know how she's doing.