If a form input field in a web-form is set to multi-line, the document is sent for review with no way for the next signer to be able to view content they are signing. This seems like a legal liability, in addition to a severely broken interaction.

This is unacceptable; it is, at the least, trivial for a form-filler to hide text without the signer being aware. If there is a multi-line field, there needs be either:

1) A way to force signers to "expand" the multi-line boxes before signing
2) A way for Orgs to "approve" forms that permits scrolling without catching the legal entanglements of signatures.
or to establish some way for Web Forms to be used for approval processes in a way that is separate from legally-binding signature