I've wondered about this a fair deal and here are my thoughts
There is no way to tell, we don't know what he is working on day to day, and it would be counter productive to demand this. Lately they have been working on their grant applications, meaning no direct progress recently but longer term if they get it its very worth their time. Is it, only time will tell. They could be on the brink today, which means it was a waste of time (since it will take time to get the money if its even approved), it may take a few years to make significant progress which makes this time spent an extremely smart decision.
They appear to be scanning everything they can simultaneously which is great and any one of them could lead to a surprise profound discovery soon, but it may not, it may take a while. Only time will tell because the condition is obviously caused by something but how hard is that something to find, we won't know until its found.
His cell stress discovery may be a core piece of ME/CFS, a downstream effect or only peripherally related. Until its identity and cause is found and pathway identified we won't know. Also his drug assay would likely be symptom control if it works, if it alters, degrades or denatures the molecule causing the block it won't be affecting the block's source since that source is not included in the test. Thats great if something controls the symptoms but its not a cure. Of course that would probably be good enough for us if it gets us functioning again and is hopefully low risk and low side effect. We would also have to be ready for compensatory effects.
A cure is more difficult, it all depends on the cause. A treatment for the actual disease mechanism will be more work, it could be found by accident (a la Rituximab) or knowing how the disease works could lead to targeted treatments. If for example its caused by intestinal bacteria then developing a treatment to eliminate it would be the cure. If its auto immune its probably gonna be much more difficult. If its an on/off switch it could go both ways if there exists a drug to reset it. If it is genetic, environmental or some other cause its impossible to say how it could be treated till we know what it is and can get to work on attacking it directly.