Dear User,
Thanks for writing back to us.
As per the further concern, I would like to share my knowledge on it i.e., the Attachments columns in the SharePoint Online list/library is a hidden column where it’s not supported for editing the item in the Grid view and not recommended to change the change name.
However, I understand you have altered the name of the Attachment column via Edit in Grid View, but the same steps didn’t work for me where clicking on Rename doesn’t respond anything and I have tested the same is multiple lists.
Note: It’s not possible via out of the box way in the SharePoint Online because the Attachment columns is not displayed in the Columns of List Settings or even Item Content Type where the metadata of the new item comes from.
Moreover, I believe you can change back the name of the Attachments column via integrating through Power Apps, since you initial requirement need to check whether integrating the list with Power Apps can achieve your requirement, you can post both of your concerns in the Power Apps and see whether it can be changed.
Hope you can understand and appreciate your patience with us. Have a good day!!
Best Regards,
Sophia