How to get taxonomy tree with path auto token?
Found it. Token should look like:

[node:field_structural_category:entity:parents]


It appeared (I think) after I changed reference field from multiple to accept only one value.

While it was accepting multiple values I could access first 3 elements, but not their parents. So this option is available only for single value fields. I see that lot of tokens are missing when tag reference field is set to accept multiple values. Bug or feature - can't say.