It is really hard for me to say what is going on in there, but if it doesn't smell like nail polish or vinegar, and doesn't smell like rotten eggs, you may ultimately be okay. Traditional meads do tend to be less infection prone, but melomels with fruit can have a lot more issues. With that starting and current gravity you have close to 16% ABV (which is more that 71B usually produces) and that really does help.
However, the risk of infection still exists, and if you leave that much headspace in a batch, it is an open invitation for acetic acid bacteria. They can survive easily enough in 17% alcohol, so you don't want to make it easy for them by giving them space with air. Malolactic fermentation can occur spontaneously with berry batches (or any malic acid containing fruit). The bacteria exist on the skin and will survive the fermentation process to start up when the yeast die down. At 16% ABV, you are at the upper limit for their tolerance, but occasionally they can be active. Treating with SO2 (metabisulphite) and keeping the temperature cool, and the pH low all help prevent unplanned MLF.
Even if you don't have a spoilage organism, old fruit particles sitting in a batch can lead to off odors (especially sulfur), and I would try to prevent that from occurring.
What I would do now, if this batch doesn't taste spoiled, is to rack underneath that stuff on the surface, leaving a good bit behind (don't worry about some loss), and make sure it goes into a container that you can make sure leaves no headspace. I would treat with at least 1 Campden tablet per gallon (or the equivalent in Kmeta powder). I'd try to keep it someplace cool (below 70F) and wait to see what happens. Hopefully it isn't infected, but if it is, this may salvage it.