NumberFormatter has a symbols method that takes a DecimalFormatSymbols and another that takes a NumberingSystem. The method that takes the NumberingSystem was designed to make it easy to declare Latin digits.
Markus said in the design doc:
I want either a version that takes just the NumberingSystem name (String), or a version specifically for ASCII digits. – withSymbolsForASCIIDigits() or similar
I would like to accept this as design and unscheduled.