The phrase "mostly able to" is correct and usable in written English.
You can use it to describe something that has been successful to a certain degree, but not entirely. For example: "The project was mostly able to meet its goals, but some unforeseen problems arose which prevented complete success."
The inverter was mostly able to handle these spikes, but would shut down about every 15 minutes.
"While technically a ghost, the rat ghost has slowly been gathering strength and at this point is mostly able to interact with real-world objects.
Mr. Dyson is mostly able to convey the gist and assess the importance of each leap forward and fill his book with humanizing glimpses of genius at work.
But the comprehensive schools used almost the same curriculum as the grammar schools had and we discovered that the two-thirds were mostly able to cope with it".
Gehry never liked the way architectural competitions structure the relationship with clients, and after the success of Bilbao, he was mostly able to forgo them.
When Kuwait recorded temperatures of 54C this summer, the highest ever recorded in the eastern hemisphere, its relatively wealthy citizens were mostly able to combat the raging heat by turning on the air conditioning.
He is grateful to not be among them, to mostly be able to regulate his desires.
So far, synthetic LCEs have mostly been able to deform in only one or two dimensions, limiting the structures' ability to move throughout space and take on different shapes.
Banks in countries that moved from a regulated to a free interest rate system have mostly been able to transfer the higher cost of funding to borrowers, said Mike Werner, an analyst at Sanford Bernstein in Hong Kong.
For the past eighteen months, the twenty-seven-year-old Quinn has received a cavalcade of similar threats, which have created an ambient hum of menace in her life, albeit one that she has mostly been able to ignore.
Police on both sides of the Irish Sea have mostly been able to contain its threat.
