The phrase "remaining challenge" is correct and can be used in written English.
For example: "Despite our advancements in the field of science, the remaining challenge of curing cancer persists."
"That's the biggest remaining challenge.
When Lennon departed, a lack of appetite for the remaining challenge was a crucial factor.
Two USW members at the back of the hall give a flavor of the remaining challenge.
Our remaining challenge, though, is to better engage with organisations for disabled people (DPOs).
The greatest remaining challenge lies in Asia, where most measles deaths are in India, Pakistan and Indonesia.
With so many options for synchronizing, the only remaining challenge is actually locating the files you want to sync.
A significant remaining challenge, officials said, is that the country has grown tired of pandemic flu warnings.
The remaining challenge was to take the obelisk apart, so that it could be moved, without damaging it further.
One remaining challenge is the lack of electricity, which is needed for lighting and running sterilising and other equipment.
A key remaining challenge is to overcome is the risk of going it alone by taking collective action.
IF those tech teething problems can be solved, the big remaining challenge will be attracting more traffic at Google's expense.
