As yet another person with significant web experience (20 years, projects up to £10m but mostly around the £50k-£500k level including years inside agencies selling such projects) this is all worrying.
There are first-order obvious questions around projects that are over ambitious and agencies that make money out of people's ignorance and inexperience (indeed that is part of the business model of most agencies) stupidly high maintenance costs and general over specification to satisfy the desire for one system to rule them all. Generally stopping and taking a good look at what you have and need is probably a good idea at this point. If the critical part of the project is infrastructure then how are we doing on that? What is the least we can do to solve that problem? What are the minimal set of features we can use to run events? How can we make those as easy and pleasant to use as possible? How is that ease balanced against the cost? You need an approach to that too.
There are second-order questions about system design and intent - like why a monolithic website/management system? One of my favourite exercises when reviewing or writing briefs is how much of this specification in front of me could I do with google docs and forms and a routing engine like IFTTT or Zapier? The answer is usually around 80-95%. Add a marketing/story website on top from a platform provider like webflow or square space and add stripe (the expensive bit). I appreciate that is a bit challenging as a set of ideas and that the time for them is past, but nevertheless there is was an opportunity here to just to leap over the whole pile of spec-driven nonsense. I suspect a tech person from the team will give me a hundred reasons why the current approach is the best, and I would be happy with a good explanation, but I would want to know that a cloud-based free-tools MVP approach had been considered. It is the modern way for a good reason. And most web agencies are explicitly not structured to offer that kind of advice or service because it is not profitable for them.
Third-order is organisational. My casual observation is that the Audax clientele has a strong Venn cross-over with Technical, IT and Web pros. While this population will never be of one mind it seems wasteful to not recruit some of their expertise. Indeed I offered mine (to read specs and briefs etc) and was thanked but never contacted. I have no particular problem with that and I am grateful that there are people who put in this amount of time for nix and I hope to join their number when family commitments subside a little. This bit is about being grateful for volunteers but balancing that with getting good advice. There is no easy answer to that, but it seems a little odd to not call on that expertise in the membership without devaluing the contributions of the generous volunteer core.
Over the years I have noted that there is a strong correlation between expense and structure of the organisation commissioning digital work. It is simply easier for a Board to cope with Specs and costs rather than get their heads around alternative approaches. As a web practitioner I see this a lot - projects look like organisations that start them, even when that form is inappropriate. A fact of life. Unfortunately this often means that larger more formal organisations get their lunch eaten by upstarts - this is where the SWOT analysis comes in - who are the 'threats' to AUK, what are the opportunities etc. Again more about strategy than IT, but my observation is that organisations are much more likely to start a project to deliver what they *think they want* than take a good long look at themselves beforehand. Then, with over runs, the project then becomes highly contested and becomes an expensive and tortuous defacto soul-searching exercise. I think we can see that playing out here. Again, horse has bolted on this one, but a good one for the lessons-learned list. Money spent on direction and strategy is often resented in organisations but it saves you a ton of cash in the medium term.
Finally I love my Audax riding, I am not particularity bothered about the price rise and generally I actually don't really care how well the board functions. I suspect this appreciative apathy is quite common. I don't excuse this apathy and acknowledge that I am not a great example of the charitable individual. The collapse of the organisation would, of course, be a blow and should be avoided but I would be really troubled if it was a failed IT project that did it. Projects can be paused, saved, rewritten, renegotiated, abandoned. There is always hope, but often admitting a feckup is the right place to start. I genuinely wish the board all the best in this, it's in no one's interest for this to become a collapse.