CV is functionally irrelevant for these things. Yes you might need to submit it but I've never seen it deciding anything...and well I've done a ton of these. It's unfortunately a game that is very strongly self-reinforcing. Let me explain

Generally it goes something like this:

Director in country A phones partner in your home country B (they probably went to uni together) saying bro I'm in trouble lend me one of your good people. Partner thinks to himself well if I send him someone bad i'll look like an idiot...better send someone solid. Well I've sent Anomaly to 3x secondments already and he's crushed it so lets send him again...just seems safest. It just snowballs from there. Those dynamics drive this, not your CV font.

Which I realize doesn't actually help you. Best advice I've got on getting started is don't be fussy and be flexible. You've got to break into that cycle somehow. Some of those projects I did definitely weren't glory-laden. But it did help me establish a rep for getting sht done no matter what the task is.

Worth pointing out that just because my context was networking driven doesn't mean other offices aren't purely CV driven. Or put differently just because I haven't seen it (and can thus say I've never seen it) doesn't mean it doesn't exist at all. Perhaps there are offices that assign secondment via CVs? Doesn't seem probable to me but hey...who knows.