As I recall, the Catalogue of Voices isn't described as being limited just to the behaviors people demonstrate when being tested to see if they are Godspoken or not, though following an already-known ritual during the test would make it pretty easy to identify one while it's happening. It's a catalogue of all known Godspoken behaviors.
For example, had Qing-jao simply been bent over on the floor but not moving her body (maybe tracing the lines with her eyes alone) they might not have identified her ritual behavior at all, perhaps believing her to be in a posture of despair or exhaustion. Had she been frantically racing around the room, laying on the floor or not, they might have interpreted her behavior as something other than a manifestation of her OCD even if she had been tracing lines all the while.
Her OCD could still exist, but her mode of coping with it might not have been recognizable to the observers. Indeed, that was the case for Qing-jao: until her father realized precisely what she was doing and pointed it out, the observers did not know that she was engaging in an obsessive compulsion.
The following is drawn from experiences with my own OCD, and is not based in textual evidence from Xenocide. It could be possible for obsessive-compulsive behaviors to manifest in an environment where the specific ritual might be stunted or impossible.
There are two relevant considerations for checking-for-accidental-murders while being tested:
- Ability to fully carry out one's compulsive behavior is not a
meaningful element in whether or not that compulsion exists or is
- Rationality (at least, rationality which fits the objective details
of a situation) is not really a factor in obsessive-compulsive
The latter is important because it means that there does not need to be a "triggering event" which starts the cycle of compulsive behavior. There need not be any evidence of a murder, or of anyone having ever been in the room before at all, to drive the need to check. It is fundamentally internal to the mind of the person doing the checking.
The former matters because, whether or not one can do a meaningful job of checking for accidental murders, the (largely) irresistible drive to do anything you can will likely prompt one to do... anything they can. The specific instance of that effort could be carefully examining the room for evidence of such a murder, whether or not any exists or which the subject feels exists. It could just as easily be an unshakable conviction that a murder did take place in the room, and demanding that the observers investigate further or provide information about it.
The key elements the testers are looking for are almost certainly the hallmarks of OCD (plus any Godspoken-specific features which may exist): anxiety about the grease on the person's hands, which builds as efforts to clean the grease off fail, inability to focus on things other than the grease, and any repetitive, arbitrary behavior (particularly if it becomes more prominent as the anxiety builds). If the anxiety seems to be eased after some behavior, especially as that behavior is repeated, that's a good sign that OCD may be present.
Also, though it's underemphasized in the book, while Godspoken tend to have one ritual that they engage in while "communing" it is not the only obsessive-compulsive behavior that the Godspoken display. Consider that one of the signs that might prompt a person to be tested in the first place is excessive handwashing.