Trade agreements usually contain provisions for dispute resolution. Back before 2016 the big boogeyman was ISDS (investor-state dispute settlement).

If a state made a bad deal they can either renegotiate it (eg. negotiate in a fee to cancel the whole contract) or try for arbitration (and the tribunal might set a fee for cancellation), or assert their sovereignty.

Of course with China everything that reaches political circles becomes a power-play, but at least in the first two cases they are less motivated to respond in kind (ie. levy tariffs or fuck with the business of Australian companies in China).