The phrase "a daunting task when" is correct and usable in written English.
It can be used to introduce a situation or condition that makes a task particularly challenging or intimidating.
Example: "It can feel like a daunting task when you have to complete a project with a tight deadline."
Alternatives: "a challenging endeavor when" or "a formidable job when".
Building a capacity for resilience might be a daunting task when one considers the multitude of components, processes, and interactions that take place within and beyond a city's physical, logical (i.e. legal), and virtual (cyberspace) boundaries.
But in writing so authoritatively about culture, photography and every aspect of cinema, from sci-fi to the nouvelle vague, she set herself a daunting task when it came to stepping behind the camera and becoming a lady of images.
He allowed that Switzer faced a daunting task when he was hired in March 1994 to take a team that had won successive Super Bowl championships to another title.
Building a case for or against a group of hackers is a daunting task when, on top of the reality that no similar legal cases could be used as reference (since none existed), even the evidence itself was wrapped in several layers of jargon.
While this can be a daunting task, when a foundation of goodwill and trust is established, this cannot only be accomplished without excessive stress, but can enhance and deepen the connection that both partners share.
If you are interested in aromatherapy, I know it can be a daunting task when you are first faced with so many scents that it is very difficult to figure out which one to use and for what symptoms.
And many startups have to conduct and implement beta testing of sites, surveys and analytics internally, which can be an daunting task when you are launching a site.
Building them can be an especially daunting task when the business itself is unsure of what capabilities are required.
This can be a daunting task, especially when you're facing it on your own.
Mitigating multiple threats is a daunting task, particularly when funding constraints limit the number of threats that can be addressed.
Undergraduate curriculum revision is a daunting task, particularly when new accreditation criteria clearly call for substantive changes in how baccalaureate generalist nurses are educated.
