April 9. On this date in 2018, the UHJ wrote "As you know, the Arabic Bahá'í Writings are not translated into the Persian language based on guidance of the beloved Guardian. There are no authorized Persian translations of any of the Arabic Writings, including the Kitáb-i-Aqdas and the obligatory prayers, and publication of any Persian translation of the full text of an Arabic Sacred Text is not permitted."

April 9. On this date in 2018, the UHJ wrote "As you know, the Arabic Bahá'í Writings are not translated into the Persian language based on guidance of the beloved Guardian. There are no authorized Persian translations of any of the Arabic Writings, including the Kitáb-i-Aqdas and the obligatory prayers, and publication of any Persian translation of the full text of an Arabic Sacred Text is not permitted."

9 April 2018
Transmitted by email
Dear Bahá’í Friend,
The Universal House of Justice has received your email letter of 23 September 2015 expressing your concern that lack of translations of Arabic Bahá'í Writings into Persian may be preventing Iranians who are not proficient in Arabic from understanding the Arabic Writings, such as the Kitáb-i-Aqdas. We have been instructed to write to you as follows. The delay in our reply is very much regretted.
Your seeking the advice of the House of Justice is warmly acknowledged. As you know, the Arabic Bahá'í Writings are not translated into the Persian language based on guidance of the beloved Guardian. There are no authorized Persian translations of any of the Arabic Writings, including the Kitáb-i-Aqdas and the obligatory prayers, and publication of any Persian translation of the full text of an Arabic Sacred Text is not permitted. Latitude has been given, however, to using a personal translation or a gist of a passage in Persian for the purpose of enhancing understanding of the Writings, and these may be shared for this purpose with a few others—for instance, in the context of a study group. Moreover, the House of Justice has previously indicated that adding diacriticals to the Arabic words and explaining the meaning of difficult words are also acceptable means of assisting the friends to gain a better understanding of the Writings in Arabic.
Your concern about the ability of Iranians to study the Bahá'í Writings is appreciated. The House of Justice has indicated that care should be taken that limitations in understanding the Arabic Writings of the Twin Manifestations of God do not become an obstacle to reaching the masses of Persian-speaking peoples, who appear to be among the most receptive populations at present. It is hoped that the measures outlined above will prove to be adequate.
Be assured of the prayers of the House of Justice in the Holy Shrines that your services to the Cause of Bahá’u’lláh may be blessed and confirmed.
With loving Bahá'í greetings,
Department of the Secretariat

Similarly, on February 1, 2018, the Universal House of Justice wrote "That the Arabic Bahá’í Writings are not translated into the Persian language is based on guidance of the beloved Guardian. There are no authorized Persian translations of any of the Arabic Writings, and publication of any Persian translation of the full text of an Arabic Sacred Text is not permitted."

Persian translation of Arabic verses
Universal House of Justice
Transmitted by email
Dear Bahá’í Friend,
1 February 2018
The Universal House of Justice has received your email letter of 7 November 2014 about the translation of the Arabic Writings into Persian. It has considered your questions regarding this matter and has instructed us to write to you as follows. The delay in doing so is deeply regretted.
That the Arabic Bahá’í Writings are not translated into the Persian language is based on guidance of the beloved Guardian. There are no authorized Persian translations of any of the Arabic Writings, and publication of any Persian translation of the full text of an Arabic Sacred Text is not permitted. In his letters to believers in Iran, Shoghi Effendi also exhorted the friends to recite the Obligatory Prayers in Arabic. However, drawing upon an individual’s translation of these Prayers or other Tablets in order to aid one’s understanding is, of course, permissible, although such personal translations should not be recited in Bahá’í gatherings. No issue should be made of what individuals do in private prayer.
Latitude has likewise been given to using a personal translation or a gist of a passage in Persian for the purpose of enhancing understanding of the Writings, and these may be shared for this purpose with a few others — for instance, in the context of a study group. Further, the House of Justice has previously indicated that adding diacriticals to the Arabic words and explaining the meaning of difficult words are also acceptable means of assisting the friends to gain a better understanding of the Writings in Arabic.
In light of a number of factors, Tajik and Persian are for practical purposes treated differently.
It is hoped that the above information will be of assistance. You may rest assured of the loving prayers of the House of Justice at the Sacred Threshold.
With loving Bahá’í greetings,
Department of the Secretariat

To summarize rules of Bahá'í translations...

Arabic works cannot be translated into Persian.

Persian works cannot be translated into Arabic.

Persian and Arabic works can be translated "into Oriental languages such as Turkish and Urdu."

Persian and Arabic works can be translated into English.

Persian and Arabic works cannot be translated into European languages.

English works can be translated into European languages.

For further reading, please see "Persian, Arabic, and Provisional Translations", "Translation and provisional translations", "Unveiling the Hidden Words, by Diana Malouf: Commentary on "Translating the Hidden Words,' review by Franklin Lewis", a letter dated June 27, 1933 from Shoghi Effendi to Adelbert Mühlschlegel about Bahá'í orthography, a letter dated June 30, 1999 from the Universal House of Justice outlining its procedures for approving provisional as opposed to authorized translations, and a letter dated February 15, 1957 from Shoghi Effendi to French Bahá'ís.