Hi Khrystyna,
Thanks for raising your concern.
The CostPerConversion field have yet to be supported on the keyword selector of Google Ads scripts. As a workaround to filter the keywords by costPerConverson, you may try to follow the instructions provided below.
1. You may try to utilize the Google Ads scripts reporting and set the report type as KEYWORDS_PERFORMANCE_REPORT. You may refer to the sample scripts provided in this link for reporting.
2. Then, Create a filter for CostPerConversion.
3. Lastly, use the return value of Criteria field in the keyword selector of Google Ads scripts.
Please let me know if you have questions/clarifications.
Regards,
Ejay
Google Ads Scripts Team