Just reading this very interesting paper by Brit Brogaard comparing timid modal fictionalism with "holistic ersatzism" a la Nolan, Sider, et al (I've just noted that Sider credits this paper by Leeds' very own Joseph Melia as one source of the idea). Still thinking about the content at the moment, something about the terminology in this area re-struck me.
As currently used, modal fictionalisms are positions that endorse something like the following biconditional
Possibly P iff According to the fiction of possible worlds, P*
Strong modal fictionalism is the natural thought that we see this biconditional as in the service of possibility-talk to talk about what holds according to a fiction. That is a fictionalism about modality.
Timid modal fictionalism is a view that denies this. Rather, we take modality as primitive (or reduce it in some other way), and read the biconditional left-to-right as partially defining the content of the fiction.
But is this really a modal fictionalism at all (in the sense of a fictionalism about modality)? When I first read this stuff, this issue threw me totally---I didn't understand what the point or purpose of timid fictionalism was meant to be---until I realized that it is really a kind of fictionalism about possibilia and worlds-talk. So it's not a modal fictionalism (/fictionalism about the modal operators), timid or otherwise; it's a possibilia-fictionalism, as strong as you like.
I guess I can see why Rosen chose those names (you might take the domain of modality to cover modal operators+worlds-talk+possiblia-talk, and then modal fictionalism is strong or timid to the extent that it's a fictionalism about all or only some of those bits of modal talk). The cogniscienti will be well aware of what's intended: but it wasn't what the terminology suggested to me at first.