“Tant pis” is an interjection, an expression - it doesn’t translate exactly to an English phrase, but is used in situations where in English we might say for example : pity, what a shame, too bad, doesn’t matter or indeed, never mind with varying ‘intensity’ etc  The meaning and ‘strength’ of expression will be conveyed by the context in which it is used, intonation, volume of speech, body language etc  The same also applies to many expressions in English eg ‘tough luck’ or ‘too bad’ can be anything from sympathy through mild expressions of understanding to dismissal of concerns etc

 https://www.wordreference.com/fren/tant%20pis