SANEWinDS does not appear as twain interface
Those applications are using WIA instead of TWAIN. You might want to check out WIASane.
The SANE backend for your scanner appears to be reporting a page length shorter than required for A4. Are you trying to create a PDF? Do you get acceptable output when you set the page size to "Maximum"?
Installation
State of Development
This should be fixed in version 1.0.7786, just made available for download.
The PDF page size issue should be fixed in version 1.0.7786, just made available for download.
Package updates