I don’t see that the EC needed to call an EGM to decide whether to engage a lawyer to attend another general meeting, within the above-mentioned limits for legal costs.
A function of the EC is to plan meetings and develop proposals for the OC to consider. If the EC thinks that it would be beneficial to engaging a lawyer to explain certain matters to a meeting and answer questions then I think that is within their function. Similarly, an EC might decide that some other sort of proposal could be better explained to owners and explored by a general meeting by inviting an engineer or an architect to attend the meeting. IE, in principle, I see nothing wrong with an EC engaging appropriate experts to advise on matters, and, on occasions, deciding that the best way for that advice to be communicated would be in person.
The lawyer may or may not be useful and the EC’s proposals may or may not be ideas that will be supported by the OC at the general meeting, but that is another matter. At least you have been given the opportunity to directly question the lawyer about whatever is proposed.