The phrase "a highly complex task" is correct and usable in written English.
You can use it to describe a task that involves many intricate or complicated elements, often requiring significant effort or skill to complete.
Example: "Developing a new software application can be a highly complex task, requiring collaboration among various teams."
Alternatives: "an extremely complicated task" or "a very intricate task."
Policy makers thus face a highly complex task.
Balancing supply chain sustainability with enterprises' commercial and societal obligations is a highly complex task.
However, designing these rehabilitation processes is a highly complex task, since it involves the analysis of the initial structural condition and the safety verification.
Untangling Scotland's banks from the broader British financial sector would be a highly complex task were Scots to vote for independence, because both RBS and Lloyds Banking Group were bailed out by British taxpayers after the financial crash.
Retrieving the distribution of aerosols in the atmosphere via remote sensing techniques is a highly complex task that requires dealing with a wide range of different problems stemming both from Physics and Mathematics.
Restructuring a firm under time constraints is a highly complex task.
Shopify makes it easy to build a transactional website without all the hassle, which takes much of the guesswork out of doing what some would consider a highly-complex task.
Voice-automation can "smarten" a home phone or feature phone, enabling users to complete highly complex tasks with a simple voice command.
These have proven to be highly complex tasks, and an integrated vision of kinome networks is required to optimize for the best combinations of targets.
Both required tremendous manpower, equipment and money, as well as highly complex tasks, all in a compressed time frame.
These can be highly complex tasks like driving a vehicle or playing Go, or translating text from one language into another.
