Greetings, Andrew, and thank you for reaching out to Ask Extension/Ask a Master Gardener. I’m happy to assist with your question.

Since you're experienced with composting, you’re likely familiar with the process composted materials go through before it's fully mature. Just to clarify, is your wife looking to plant directly into finished compost, rather than compost that’s still maturing in the garden beds? If the compost isn’t fully broken down, it can create an environment that's not ideal for most plants. Unfinished compost tends to have high heat levels and inconsistent Ph levels & nutrient content, which could stress plants. 

I’ve heard anecdotal reports of sweet potatoes and certain cucurbits growing well in compost piles, though I have not found research-based evidence to support this. Generally, compost should be allowed to mature for 4-6 months before it’s used in planting.

If you decide to plant directly into pure, mature compost, be aware of potential issues like rapid drying, compaction, nutrient imbalances, and possible heat. These factors can negatively affect plant growth. Compacted compost may even become "hydrophobic," meaning it repels water instead of absorbing it, which could cause additional problems.

Below are some research-based resources that may help you and your wife make a more informed decision. And I want to commend you for your efforts in composting—it’s a great practice!