"proficient at working" can be a correct and usable phrase in written English.
It describes someone's strong ability or skill in performing tasks or duties. Example: Tom is proficient at working with numbers, which is why he excels in his job as an accountant.
The bottom line is, I'm not proficient at working anything more complex than my blow dryer.
In part, that is because the duo was as proficient at working with charts and session musicians as it was with drum machines and vinyl.
But I do think we need to become more patient and technically proficient at working with the global institutions which, step by step, will make a major difference in the long run.
The senior Aboriginal researcher, proficient at working in cross-cultural contexts, supported the research process and analysis from an Aboriginal perspective.
In their motoring through Spain he had become proficient at this work and so proceeded rapidly now with only the taillight of the car as illumination.
Pereira-Smith also pushes her postdocs to become proficient at communicating their work through giving talks and writing papers and grant proposals, Gorbunova adds.
Limited English Proficient women are much more likely than their English-proficient counterparts to work in service occupations.
Do Your Research Skilled at digging for case studies at work? Proficient in cyberstalking an ex?
A maintenance contract for the wagons lapsed in 1900, as the men at the works had become proficient at repairs.
She appears to be proficient at life on the run.
She is proficient in Spanish, French, and Italian, and spent a summer while at Harvard working for "Let's Go: Italy," researching and writing content for the budget travel guide.
