FM-World Locate data_mirror/data_de/null/0/com.android.phone/files/Carrierconfig-com.google.android.carrier-(ID_sim_card).xml
I've seen this before. The information is out of date and/or not applicable to GrapheneOS.
Location and format of configuration file names have changed, in the build they are:
CarrierConfig/assets/carrier_config_carrierid_(ID_sim_card).xml
The larger issue is that your suggestion of what to edit/delete, doesn't exist.
The entire content of one of the country/providers in question is:
<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<carrier_config>
<boolean name="show_4g_for_lte_data_icon_bool" value="true"/>
<string name="default_vm_number_string">121</string>
</carrier_config>