OK, looks like I was wrong. The PHEV version was introduced for 2014 (and discontinued after 2015), but they kept selling the non-plug-in version alongside.
It also looks like a number of our sources have the hybrids listed under regular ‘Accord’, not ‘Accord Hybrid’ specifically’. So for now, I would suggest searching the ‘Accord’ model, and adding “hybrid” and “plug-in” to your keywords.
We are planning to add a ‘fuel type’ filter soon, and will look into whether we can differentiate between non-plug-in and plug-in hybrids. We’re also looking at adding a ‘trim keywords’ field, which would allow you to search for ‘plug-in’ in the model or trim names, as opposed to anywhere in the description (where you will also get silly things like “aux plug-in”). Hoping to have those ready before long, along with sorting out the model inconsistency.