I think the process would be something like this.
The new committee resolves that the Owners Corporation will get instructions from a lawyer re issuing a demand to the members of the committee that started the legal action without approval for incurring obligations and making payments from the Owners Corporation funds without proper approval of a general meeting. There should be supporting documentation for the likely cost (it is for advice only, not for actually doing anything) to substantiate that there is no requirement for a general meeting to approve.
The advice will be that those owners should be advised of the proposed legal action, and a notice prepared and distributed for a general meeting at which the proposal for recovery of the unapproved expenditure from those committee members will be put to the owners. The Treasurer at the time should be specifically identified as the responsible person, but the liability would actually be joint and several.
Meanwhile an application is made to the Tribunal for awarding of costs that excludes from the special levy all owners who were not part of the Committee at the time that the payments were made.
With those two actions in front of them the owners who spent the money without approval will come to an agreement to meet the expenses by levy contributions based on their responsibilities, and a notice of adjudicated agreement can be lodged with the tribunal. If that doesn’t happen, the owners can then consider whether or not to take things further.