The rules for fn:parse-json say:

If the escape option is set to true, escape sequences are retained in their escaped form, whether or not they represent valid characters.

(This is in rule 3 underneath the options table. I would have expected to find it in the "escape=true" row of the table, but never mind.)

This rule means that, for example, parse-json("\u0025" map{"escape":true()}) returns "\u0025" rather than "%".

For the fn:json-to-xml() function I cannot find a corresponding rule. There doesn't seem to be anything that dictates whether "\u0025" should end up as <string escaped="true">\u0025</string> or as <string>%</string>.

I suggest we adopt the same rule (and move it into the table, in both cases.)