If I`d like to map special stock field in a module with leads, where I have to use a custom field the field names do not match because of the _c and therefore the mapping leads -> module does not work.
Unfortunately, your field names donβt match, but for the CRM to carry the values through conversion, the field names must match.
You could deal with this by creating some custom code to carry over specific fields, or you could create this custom field on the module where it doesnβt exist, just to ensure that they exist on both modules.