Are there Reformed associations that prohibit or strongly discourage member churches from the singing of hymns with non-biblical texts? Or, is that something that all Reformed associations leave to the discretion of the member congregation?
There are some denominations which hold to "Exclusive Psalmody" and/or "Non-instrumentation". I'm sure someone else can give you a list of all of them. There are several members here to belong to churches which practice this. But one that comes to my mind immediately is the RCPNA (Covenanters).