We do this:

		DocumentFieldMetadata fieldMetadata = documentBuilder.getTypeMetadata().getDocumentFieldMetadataFor( fieldName );
		if ( fieldMetadata != null ) {
			if ( fieldMetadata.isNumeric() ) {
				perFieldQuery = createNumericRangeQuery( fieldName, rangeContext );
			}
			else {
				perFieldQuery = createKeywordRangeQuery( fieldName, rangeContext, queryContext, conversionContext, fieldContext );
			}
		}

Thus, if there is a custom MetadataProvidingFieldBridge that overrides the field type for its default field, we completely ignore this.
Maybe the simplest solution would be to take the output of MetadataProvidingFieldBridge into account when setting the value of DocumentFieldMetadata.isNumeric()... ? See org.hibernate.search.engine.metadata.impl.AnnotationMetadataProvider.isNumericField(NumericField, FieldBridge).