This is exactly why configuration/serialization formats should make as few assumptions about value types as possible. Once parsing's done, everything should be a string (or possibly a symbol/atom, if the program ingesting such a file supports those), and it should be up to the application to convert values to the types it expects. This is Tcl's approach, and it's about as sensible as it gets.

...which is why it pains me to admit that in my own project for a Tcl-like scripting/config language[1] I missed the float v. string issue, so it'll currently "cleverly" return different types for 1.2 (float) v. 1.2.3 (atom). Coincidentally, I started work on a "stringy" alternative interpreter that hews closer to Tcl's philosophy (to fix a separate issue - namely, to avoid dynamically generating atoms, and therefore avoid crashing the Erlang VM when given potentially-adversarial input), so I'm gonna fix that case for at least the "stringy" mode (by emitting strings instead of numbers, too), knocking out two birds with one stone for the upcoming 0.3.0 release :)

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[1]: https://otpcl.github.io, for those curious