When the description starts with "we are looking for planets with ammonia atmospheres", and later it says "ammonia worlds", it sounds like it's just a synonym for the former, unless you already know that "ammonia world" is its own thing that's not just a planet with an ammonia atmosphere. After all, "planet with ammonia atmosphere" is long to say and type, so "ammonia world" sounds just like a shorter synonym for it, so one doesn't have to keep repeating that longer expression.
That's precisely what happened to me. That's exactly how I interpreted it. I did not know that "ammonia world" is its own thing, which is different from a planet just having an ammonia atmosphere. I knew there is such a thing as "water world", but I had never encountered nor heard of an "ammonia world" so I didn't know that they exist, and just assumed that it was being used as a synonym for "planet with an ammonia atmosphere".
I wouldn't be so ed off if it hadn't cause me to interrupt a planned quite long exploration trip, while I was already advanced for quite a while. When I started encountering planets with ammonia atmospheres along the way I remembered the CG and checked what it was, and I saw that, indeed, "planets with ammonia atmospheres", I thought that it would be a nice bonus for scanning those planets so I came back to the bubble, scanning ammonia atmosphered planets along the way, only to find out that I didn't get a single one counted.
Why on earth would they write "Universal Cartographics has announced a two-week initiative to locate planets with ammonia atmospheres" if that's not what they want.