New developments seem very promising

There are several therapeutic approaches currently being developed for FSHD in the laboratory. However most of them are still in their infancy. The condition is caused by the production of a protein called DUX4 that is normally not made in muscle.
There are two main ideas for therapies. The first is to block DUX4 from being produced in muscle cells. This includes the development of an adaption of the exon skipping technology and finding drugs that can inhibit DUX4 activity. The other is to reverse the negative effects of DUX4 production which includes re-balancing genes that have been turned on or off by DUX4, as well as restoring changes to muscle cells caused by DUX4, e.g. sensitivity to oxygen.
ATyr Parma’s ATYR1940 is an anti-inflammatory drug that scientists think might have a beneficial effect for people with FSHD and yes a phase I/II clinical trial is currently active and recruiting participants in France, Italy and Netherlands to test the safety and tolerability of this drug in people with FSHD aged 18-65.
For myostatin, a phase I/II clinical trial sponsored by Pfizer was conducted using = Myo-029, an antibody that neutralises myostatin. It was conducted on 116 participants in the USA and showed that Myo-029 is safe and well tolerated but there were no improvements in muscle strength or function.

There is another compound called albuterol, a 2-adrenergic agonist known to increase muscle durability and mass which was investigated as a potential treatment for FSHD. Two small scale clinical trials were conducted to test whether albuterol was able to increase strength and muscle mass in people with FSHD but no significant improvements were observed.
So you are right there is a lot of progress in the FSHD field, however more research is required to understand things like how the gene activity altered by DUX4 leads to the clinical symptoms of FSHD or why DUX4 is only produced in muscle and why some patients have non-muscular clinical symptoms. Finding answers to these questions can help design new potential therapies in the future.
Muscular dystrophy UK funds a number of projects in the field of FSHD. More information can be found on our website.
We also provide financial support for the establishment of maintenance of a national patient registry. By providing strong links between patients and researchers the registry has the potential to greatly advance our understanding of this rare condition as well as keep individuals with FSHD informed about research developments.

Please note that the development of new therapies for genetic conditions is a lengthy process, and only about a third of experimental drugs successfully complete both phase I and phase II clinical trials.