At CurrySoftware we use recfiles combined with git for all business-processes (incoming and outgoing invoices, customers, etc).
It allows us to automate everything we want with simple bash scripts. But we remain flexible because we can perform non-automated tasks manually.
>>jdemle+(OP)
Your processes made me think about a email based interface instead of a bash script, this may allows to easily interact with the database bot without knowing bash or python.
>>weeber+hc
We plan use a Telegam interface for many things (status checks, new invoices etc). Its easier and faster than E-Mail and available everywhere!
>>alvil+Xu
Harder, since they don't have an open API and don't want people using non-standard clients. The clients are open-source though, so probably you can do it.