I think it's normal to let the OP know what a peristylium precisely is in order to see if it's what he needs, no...?
That's fair enough. On the other hand, the OP had the chance to stipulate the specifications of his courtyard in three separate posts, and yet even when Imber Ranae put words into his mouth by suggesting what the OP may have had in mind, the OP side-stepped the prompt for further information and merely put forward his own suggestion of peristylium.
I don't understand why you seem to be taking this as a problem.
The only problem is understanding why you seem to regard persons requesting translations as entirely exonerated from the need to be specific even when prompted to do so, whilst apparently insisting that translators should anticipate a requester's requirements from every conceivable angle. If you are painstaking enough to be capable of such a degree of anticipation then that's clearly not a fault, but I think it is a little unfair to expect everyone to come up to your own exceptionally high standards.
Finally, the OP asked whether "the word
peristlium (sic) might suffice for courtyard". When "might suffice" was the extent of the demand, was it not reasonable to proceed on the basis that it does?