Unable to extract netwatch variable

$"sent-count".$"response-count".$"thr-loss-count".$"thr-loss-percent".$"thr-avg".$"thr-max".$"thr-jitter".$"thr-stdev"

the result is 10 9, the rest empty

Without some context it is improbable that anyone can reply with something useful.
BUT thr- become (largely) rtt-.
See:

There used to be a short hint the old netwatch docs, which is missing in the new manual:

When writing Up/Down/Test scripts for Netwatch, use the rtt-* elements instead of the thr-* elements. If the element names differ, their script-specific forms are listed in the description.

Nowhere to be found on Netwatch | RouterOS Manual

See also term "software documentation"/"proofreading" in the dictionary. Mikrotikish<->English conversion table/dictionary

The CLI Reference has the "Read Only" attributes. They are not organized by the probe types, but I believe it's the correct list: