human player rules question

I was wondering if the human player is allowed to touch the inside of the embrasure? not past the box to be clear!

No

The embrasure is part of the HP station. Per 2.2.3.1 the HP station is part of the castle wall. In the Glossary, the castle wall is part of the castle. It looks OK to me.

I think the rule you’re looking for is G4:

G4 DRIVE TEAMS may not extend any body part into the FIELD during the MATCH. Momentary encroachment through the hole in the HUMAN PLAYER STATION behind the BRATTICE while placing a BOULDER into that hole is an exception to this rule.
Violation: FOUL. Violations of this rule are likely to escalate to YELLOW or RED CARDS rapidly (i.e. the threshold for egregious or repeated violations is relatively low)

The tunnel part of the EMBRASURE is not inside the FIELD, so it can be touched. But don’t stick your hand through into the field.

Relevant rules

I read those rules, I was inferring to where the ball is rolled in if unclear. It doesn’t stay in the rules about that box.

Seems to answer the question, unless we all are vastly misunderstanding the question.