I am looking for a single word to express the idea "merely reporting a fact" in a context such as "I am not saying this complacently but X" where X is the required word representing "merely reporting a fact". Alternatively, X can also be a word simply for "reporting a fact".
The most idiomatic way of saying this in English would not be to use a single word. The most natural way to say this, in English, would be something like:
I'm not trying to make trouble; I'm just telling you the facts.
..I'm just telling you what I saw.
or something along those lines.
If you want a single word, the closest I can come up with is objectively. This has the meaning you want, but if you use it in this context, it will sound somewhat arrogant or obnoxious. It would be better to soften it:
I'm not saying this to make trouble; I'm just trying to be objective.
Also: the phrase
I'm not saying this complacently
itself sounds a bit awkward. I'm not sure exactly what you're trying to say, but I suspect there's a better way to say it.