There's the answer as to why it has stopped losing weight.
But to actually answer your question - at 25% weight loss it's going to still have a pretty 'raw' texture - but as long as it hasn't gone bad in the middle due to the extra trapped moisture, it should be safe to eat.
If you want to try and get it back on track to the ideal 35-40% weight loss area - I'd take it out of the Umai, vacuum seal it and throw it back in the fridge for a week or two to help the moisture redistribute itself evenly throughout the muscle (cutting it in half when you do this will help, plus this way you can give the middle a look see/sniff test), then return it to a new Umai to re-start the process of drying out the rest of the way.
Just my $.02, I'm sure others will weigh in here as well.