The question now that the family has revealed names of those involved, can the committee go after them? Of course this will go on trial and will be dragging the names of those involved. But I think by now, it's very obvious that with the life style of this two engineers, they should be guilty of misuse or misappropriation of public money or property and they should be put to jail by now.
But I don't know how the justice system in the Philippines. If those high officials involved themselves, then maybe they know that they can still get away with it despite the overwhelming proof like the speaker of the house.
They will just denied the allegation and prolong the investigation, as we know either the people will take actions or wait for the election to removed the current administration, in terms of any sanctions I'm not sure if how those invetigation will proceed as you mentioned, even how clear the evidences that being submitted or provided, together with the statement of one of those major contractor who can be serve as witness of this flood control issue.