“ House vows to continue impeachment probes regardless of Senate outcome”, page-19

"in fact I'd like to see Bolton / mulvaney appear "

No reason for Bolton to appear, he wasn't subpoenaed by the Dems during the 'investigation'.

No reason for Mulvaney to appear until the courts, likely SCOTUS, have decided on the legality of the McGahn subpoena.

The Dems rushed the whole sham. Impeach in haste, repent at leisure.