It's not clear to me how a stupid system like this is used in favour of, say, 5 numbers+5 numbers (4 decimals coordinates lead to a ~5.5m radius)
I'm not sure I understand what you mean with "high risk of errors on both ends", as there is no chance of mispelling. How do I know that? Because numbers are used in military standards for comms that have to be clear even through unreliable channels. Languages that have numbers which might be misunderstood specifically use a different number set (one example is the military in China).
Building your own solution when you have a GLOBALLY ACCEPTED standard that took YEARS to be agreed upon is criminal in my opinion, rescue missions on the Alps where different cultures meet being a great example why you should stick to numbers.