に足りない|にたりない

1. 1Not worth ~ing; too minor or insignificant to warrant the action or reaction.Ex. 1
2. 2Not worthy of ~; lacking the qualities that would justify the evaluation (e.g. 信頼に足りない 'not trustworthy').

A formal, literary expression used mainly in writing, commentary and speeches. It often combines with verbs such as 取る, 恐れる, 論ずる and 気にする to dismiss a matter as insignificant. With nouns like 信頼, it judges that someone or something falls short of deserving that evaluation. It is the negative counterpart of に足る, and it evaluates the thing itself rather than simply saying an action is unnecessary.

• に足る / に足りるN1「に足る／に足りる」 is the affirmative counterpart of 「に足りない」, meaning something is worth doing or sufficient for something; it is mostly used as a modifier in positive evaluations. 「に足りない」 carries the opposite meaning with a dismissive tone. The two attach the same way and are both literary, and they cannot be swapped.
• に値するN1「に値する」 is used in the affirmative to mean 'worthy of' or 'deserving of,' typically attaching to evaluative words like 「称賛」 or 「尊敬」. Its negative 「に値しない」 is close to 「に足りない」, but it emphasizes giving a formal negative judgment, while 「に足りない」 more strongly conveys a dismissive sense that the thing is trivial.
• にあたらないN1「にあたらない」 attaches only to reactions or evaluations such as surprise, worry, criticism, or praise, and means there is no need to feel or say that; it often appears as 「にはあたらない」 and has no 'insufficient' meaning. When attached to reactions like 「驚く」, the two can be interchangeable.
• までもないN1「までもない」 attaches only to the dictionary form of verbs and means there is no need to bother doing something because it is obvious, simple, or can be handled another way; it does not belittle the object, is neutral in register, and is common in speech. 「に足りない」, by contrast, stresses the object's low value, is literary, and can also attach to nouns.
• にたえる / にたえないN1「にたえない」 means something is so bad it is unbearable to watch or hear, or, as with 「感謝」, expresses being more than one can bear; 「に足りない」 means not worth doing or not sufficient to meet a standard such as trust, so the two cannot be swapped. The affirmative 「にたえる」 means 'can withstand' or 'is worthy of.'
• 〜にすぎないN2「にすぎない」 means 'is nothing more than,' limiting the object to a certain scope; it can attach to nouns, verbs, and adjectives, is not necessarily derogatory, and can even set up praise. 「に足りない」 says something is 'not worth / not sufficient for doing.' The two cannot be swapped.

に足る/に足りる is the positive counterpart ('worthy of ~'), and に値する likewise says something deserves an action or evaluation. にあたらない and までもない say an action or reaction is unnecessary or uncalled for rather than that the thing falls short of meriting it; にたえない means 'unbearable to ~' or expresses intense feeling, and にすぎない means 'merely, nothing more than'.