tagOn is used with the cur-point conjunct which is a violation agains the 7. Validation Rule

[MalteSchwenker]

Validation:
7. Verify tagOn only used on a tag defs (not conjuncts or feature keys)

The violation is in the Lib: phIot
https://project-haystack.dev/doc/lib-phIoT/curVal

i thing the tagOn tag e.g. for curVal, curStatus, curErr should be used with the y:cur def.

Please check the Haystack 3 documentation
https://project-haystack.org/tag/cur