Hi,

There might be catch I don't see, but your request sounds simple enough. As you already use GUI, there's a menu "Export/Import>Restore Metadata>Restore TIF metadata", which is supposed to do what you need.

1. Inside GUI, you select all TIF files you wish to populate with metadata,
2. Choose above menu and short explanation/guide will appear,
3. Now you select any of DNG files from which you wish to copy metadata,
-and that's it.
This way, of course, all metadata from DNG files (not exif only) is copied into TIF files. I say that, because DNG files usually contain a huge amount of (most Adobe's) XMP metadata. Thus, if needed, you can later delete (in batch again) all unwanted XMP medatada from TIF files (by using menu "Modify>Remove metadata".
I hope this was of some help for you.

Bogdan