I acidify only papers that need it, such as Stonehenge. Some papers do not need it, and I believe Fabricano is one of them. I tried it years ago and it printed beautifully without acidifying. The same with Lana Aquarelle and Arches Platine. I'm not sure though, if this is the issue, though. The example print on the left is fine. The toned example on the right isn't. Hmmm.... bad toner? Personally, I do not tone. I like the look of the untoned print. I only develop in sodium citrate. I always had problems with acetate/tartaric acid developers. I could see a lot of the metals leaching out at the start of development, and more so when fixing. What fixer do you use? I like a very simple fixer: sodium thiosulfate and ammonia. One minute.
If you cannot clear your paper after 4 minutes in citric acid, there may be a problem with your tap water. After development, rinsing with tap water that is too alkaline can cause insufficient clearing. I fill a large bucket with water and sprinkle in a wee bit of citric acid to acidify it. I rinse the print this way. It helped significantly.
Or... it could all just be bad toner.
Or... you could give more exposure. But... by clearing, fixing then toning, there shouldn't be any loss of highlights.