Is there a tool to import or verify transactions from a collection of emails or SMS messages?
It's actually going to be pretty easy to hack one up with Tasker. But I assume that guessing the account name will be the hardest, since those emails/SMS does not tend to be very descriptive.
I don't use csv import or any sort of automated posting(besides depreciation with my own tool) because of that. I briefly thought about using (local)LLM but it's honestly too big of a task for a minor convenience, since it's going to need constant refactor.
I used to import more csv/tsv/other formats, but they require maintenance, like you say. It's currently the only method supported by a few banks, so I still maintain a conversion script for them, but email/SMS would be about as good. I have thought of tracking orders and such with the ledger format, as well.
I do use ofx/qfx/qbo formats because the FITIDs make it easier for similar entries (after correcting for a flaw or two in bank implementation.) These have been less supported, as time goes on, so I like having fallbacks, as well.
I have a semi-automated import/verify method. It can either be interactive or totally automated, skipping transactions it's unsure of or approximating with an Unknown account. It generates a diff of changes that I can then tweak, if needed. It decides the category by minimal learning (only from entries that have already been matched in the files it's looking at) and custom matching functions for the system it's looking at. I typically only give it trivial or often-used matching rules. It's not perfect, but does save me some time.
If a tool doesn't already exist, I have previously used the termux SMS tool, so I'll probably look at that. If it doesn't work, I might try Tasker.
I intend to get an email sorter, so I could hook into that, too.