My question: since this is GA transaction (not transaction directly from gAds conversion tag on the website) - if I use API method an OrderIdOfflineConversionAdjustmentFeed object with correct parameters' values, can I change the conversion value (to let's say 333.33), so my report in gAds would actually look like (see the difference in last column):
I just need to know if this is possible?
If it is, I should use correct parameter's values, the most important are orderId: 'T003' and conversionName: 'Transactions (All Web Site Data)'.
You can adjust a conversion by uploading an OrderIdOfflineConversionAdjustmentFeed object when you have an order ID available instead of a click ID and conversion time. However, please note that the conversion has to already be reported in order to adjust it.
For your second concern, you can use the AdWords API to upload offline conversions into Google Ads, giving you more flexibility in associating clicks with conversions. You may use the OfflineConversionFeedService to upload the click conversions offline. Please take a look at the validation rules and Tips which help you upload them successfully. You may then use the OfflineConversionAdjustmentFeed object to make adjustments. In order to map that specific click back to the Campaign or AdGroup, you may use the Click Performance Report which will return these details. You can also add Value track parameters to the tracking template URL which will populate these values in the click URL.