Is there a way to keep Kotlin annotations only for public functions/members when obfuscating with proguard?

I am trying to obfuscate a library written in Kotlin using Proguard.

In the library I use default and named arguments. In order for these to work when including the obfuscated jar as a lib I need the flag -keepattributes RuntimeVisibleAnnotations in the Proguard file.

With this flag all private functions are no longer obfuscated, because the annotations for them contain the plain names. Is there a possibility to apply this flag only to public functions and members and to delete the annotations for private functions and members?

This is probably also connected to the fact that public members of an interface only work with the above-mentioned flag. Is there a solution that solves the problem with both the interface and the classes?

current Proguard file:

-dontwarn
-dontoptimize
-keepparameternames
-keepattributes Signature, InnerClasses, Exceptions
-keepattributes RuntimeVisibleAnnotations
-keep class custom.package.** {
      !private <fields>;
      !private <methods>;
  }
-keep interface custom.package.** {
      !private <fields>;
      !private <methods>;
  }

obfuscation result with this config:

public class ExampleClass {
    private val clearNameAttr: kotlin.String /* compiled code */
    private fun clearPrivateMethod (namedParam: kotlin.String) : kotlin.Boolean { /* compiled code */ }
    public fun clearPublicMethod (namedParam: kotlin.String) : kotlin.Boolean { /* compiled code */ }
}

desired obfuscation result:

public class ExampleClass {
    private String a
    private boolean a (String var1) { /* compiled code */ }
    public boolean clearPublicMethod (String namedParam) { /* compiled code */ }
}