For example... HANGS IN THE BALANCE: an issue (especially a dynamic between two extremes) of importance that may be decided one way or the other? Also... IT'S ALL IN THE BALANCE: success in XXXX depends on having good balance
No, in French the metaphorical idea of equilibrium is associated with the word "balance" (balance des pouvoirs, balance des paiements, balance commerciale, (TLFi); however, the idea in "hang in the balance" is "incertitude".
(TLFi II.− P. métaph. ou au fig. [Implique la not. de jugement ou d'équilibre]
(OALD) (be/hang) in the balance
if the future of something/somebody, or the result of something is/hangs in the balance, it is not certain.
As to "IT'S ALL IN THE BALANCE", where "balance" is taken literally as "the ability to preserve balance of one' body", "balance" would be translated rather as "sens de l'équilibre".
- C'est purement dans le sens de l'équilibre.
(SOED) balance 11 Stability due to equilibrium between the forces within a system; (ability to maintain) steadiness of position; transf. mental stability.