Here's a script that puts the tags of the records in the frontmost library into the comments:
On my Mac, the Finder sometimes reports an error when setting the comments of a folder. If you want to ignore the error, you could delete the line that starts with "display dialog".
tell application "EagleFiler"
repeat with theRecord in library records of library document 1
set theNames to (name of tags of theRecord)
set AppleScript's text item delimiters to " "
my setComment(file of theRecord, theNames as string)
on setComment(theFile, theComment)
tell application "Finder"
set comment of theFile to theComment
if length of theComment > 0 then
display dialog "Could not set comment of “" & theFile's POSIX path & "” to “" & theComment & "”."