JWs use the term "undeserved kindness" where others use the term "grace". Just as the original Greek term would have been more than a mere "feel-good" term, so the English rendering is more clear when it's more than mere fuzziness. Is not the JW's NWT rendering more clear in verses such as this...
(Romans 11:6, NWT) Now if it is by undeserved kindness, it is no longer due to works; otherwise, the undeserved kindness no longer proves to be undeserved kindness. [italics added by me]
(Romans 11:6, NIV) And if by grace, then it is no longer by works; if it were, grace would no longer be grace.
Similarly, JWs use the term "declared righteous" where others use the terms like "justified" (and "redeemed"). The concepts of "undeserved kindness" and "declared righteousness" are not identical but are complementary. Paul wrote the Galatians that a Christian could "shove aside the undeserved kindness of God", which JWs believe happens when a Christian doesn't allow his faith to move him to godly works. James writes that true faith must result in godly works, and he further writes that a Christian without godly works could not be "declared righteous". You can see how having fuzzy terms would make this discussion much less interesting.
(Galatians 2:16,21, NWT) [A] man is declared righteous, not due to works of law, but only through faith toward Christ Jesus, even we have put our faith in Christ Jesus, that we may be declared righteous due to faith toward Christ, and not due to works of law, because due to works of law no flesh will be declared righteous. ...21 I do not shove aside the undeserved kindness of God; for if righteousness is through law, Christ actually died for nothing.
(James 2:21,22,24, NWT) Was not Abraham our father declared righteous by works after he had offered up Isaac his son upon the altar? 22 You behold that his faith worked along with his works and by his works his faith was perfected... 24 YOU see that a man is to be declared righteous by works, and not by faith alone.