I personally think the wording is too complex and technical.
They are better put into a standard letter for people to send to EH than on a petition.
Better to have a petition that requires a single outcome, than a complicated one that EH can say has been delivered on with a few glib answers. Try not to get too fussed about the way EH go about things. What is the goal here? To get information, or action?
"It has come to my attention that the ancient monument of Silbury Hill is in serious danger of collapse, this has been known about by English Heritage since it first suffered an internal collapse in XXXXX yet the structure is still in an unstable state.
It is urgent that English Heritage address this situation as soon as possible, as further collapses have been noted, indicating this fine ancient monument is in need of immediate remedial action.
It is my desire that English Heritage address this situation with the utmost urgency."