Hi, as "NUMBER@2" expects two parameters and you want to overwrite the old mapping, then you need you specify the source type exactly the same as the existing one, which should be like this:
<set-project-type-mapping type-mapping-schema="Columns type mapping" source-type-id="NUMBER@2" target-type-id="INT">
<source-type-param />
<source-type-param />
</set-project-type-mapping>