*beth recalls a fic where she gave a newbie Seraph a headache in the Halls of Lightning; he read a paper on someone's corkboard that said "The next statement is false. The previous statement is true."*
First-off, totally ignore my meta-discussion here if it will detract from the fun of the discussion. O:> That said... ...Oh, fun, I can use the Spoiler tag!
Spoiler:
I think that it might be a good idea to acknowledge that there is, and shall always be, a bell-curve among all the Choirs (and Bands). The average Seraph may be rather uncomfortable with certain nouns and verbs being used as "expression of frustration and/or pain" -- but there will be outliers (especially among Creation and the Wind, I'd figure) who are much more comfortable with such things. Heck, some Creationer Seraphim may even be able to make puns!
Since there will be a bell-curve with skinny ends, an In Nomine game played "sane" will tend to have Superiors behaving rationally: they will usually only assign a Seraph to a swearing Role if that Seraph can handle it. (Happy or unhappy about handling it? That's a different kettle of fish, generally up to the player for PCs and the GM for NPCs.) If the "humor" dial is yoinked up a bit, then you'll get Seraphim in situations where they are both in a carefully-prepared Role and they haven't been walked through a supermarket long enough to get over sobbing about "No, no, I do believe it's not butter!"
And there's tweedling the Darkness dial, so Archangels are callous enough that they'll drop a Servitor into a situation if the Servitor has one useful purpose -- and the Servitor had just better cope with the rest of the baggage. This is also possible if the Archangels tend to be so alien that they can't really grasp that humans do this inconvenient thing, and so distant that they don't really want to hear their Servitor explaining that there's a bit of stress going on...
So to a large extent, how well a Seraph handles profanity depends on the Seraph, and the game-setting, and the player (for PCs) or GM (for NPCs).
Now, figuring out what you want on the fat end of the bell-curve? Carry on! O:>