Fun story: I was at a bank that used Excel for everything. As you say, there came a complaint from the auditors that it's not well auditable, and there needed to be "a system".
Solution: the bank put together a system that constructs (from Excel templates and the bank trading data and market data) Excel spreadsheets from scratch every day, then used those for the calculations, and stored them. But now it was "a system", so all good.
Well you can audit the code that generates spreadsheets, which seems to solve the audit problem. Kind of like I prefer reading a Dockerfile that builds a program from the GitHub repo, rather than downloading a pre-compiled package I can't trust.
sounds like a great system. we have something similar where we put excel in and out but doesn't sound as slick as that. on top of the system there is access control, versioning and such. the data gets approved and then stored in the backend to feed the regulated process.
Solution: the bank put together a system that constructs (from Excel templates and the bank trading data and market data) Excel spreadsheets from scratch every day, then used those for the calculations, and stored them. But now it was "a system", so all good.