"做事心不在焉者" can be translated into English as "those who are absent-minded in their work" or "people who are inattentive when doing things".
Both expressions convey the idea of someone being distracted or not fully focused while performing a task. The first option is more concise and directly relates to work, while the second is more general and can apply to any activity. Choose the one that best fits the context of your sentence.