The Japanese translation of the term "Time spent" field in Jira Cloud issues is currently "所要時間" but this is confusing as it could also sound like estimated/required time rather than the time consumed. 

To avoid such confusion, it is suggested to change it to "消費時間" as in the documentation below and also on the Server, or something like "費やした時間".

See the attachments for how it is currently translated on Cloud and Server respectively.

FYI, in the official documentation here, It is translated as "消費時間" here.

JP: https://support.atlassian.com/ja/jira-cloud-administration/docs/configure-time-tracking/

EN: https://support.atlassian.com/jira-cloud-administration/docs/configure-time-tracking/

(either the translation on the product or doc should be updated for consistency, but it is suggested to use the term other than "所要時間" to avoid further confusion).