Print formats: How to FORCE translation of specific part

Let’s say I have a bilingual report that I want to display same value in both English and Other Language (ie.Arabic).

Let’s imagine the report is:
Leave Type: Paid Leave
Leave Type in Arabic: إجازة مدفوعة

The translation of “Paid Leave” exists in the Translation list as a custom translation as an arabic translation (language set there is ‘ar’ in the translation record) .

I know for the fact, that the user will always choose English for printing as default language.

The html code would be

 Leave Type: <span> {{doc.leave_type}} </span> <br>
 Leave Type in Arabic: <span> {{_(doc.leave_type, ar)}} </span>

The 2nd value works if I choose “Arabic” in the printing preview, however I want to force its translation even if user chooses English.

I have tried

{_(doc.leave_type, ar)}}
{_(doc.leave_type, lang=ar)}}
{_(doc.leave_type, lang=AR)}}

None worked.

Is there a way to force translating this value from english to arabic regardless of the chosen print language?