The Arab world knows these "conversions" were phony too.
What makes you think so?
Invalidating an Islamic conversion under duress is meaningful to us westerners, but means nothing to the the Arab world. The history of Islam is full of forced conversions practiced routinely in accordance with the Koran for over thirteen centuries, not just in the Arab world, but Islamic conversions throughout the world. It's a valid conversion to them as the Koran is full of verses and quotes about how to make mincemeat of infidels who don't submit to Islam.
The Hadith, which is a compilation of books related to Muhammed, just as the Gospel is to Jesus, tell us that forced conversions are acceptable and indeed valid:
Some quotes from the Hadith relating to forced conversions:
"I have been ordered to fight the people till they say 'None has the right to be worshipped but Allah' And whoever says: None has the right to be worshipped but Allah.' waves his wealth and his life from me unless he deserves a legal punishment lusty, and his account will be with Allah."
--pp. 16-17 (Azharite]
"If a Protected Person [Dhimmi] is forced to convert to Islam, his conversion is valid. If a Harbi [non-Muslim alien] is fought against and converts to Islam - it is valid... If the [same] Dhimmi returns [to his former religion], he is not killed [like an ordinary apostate], but imprisoned until he converts to Islam [again], because there is doubt regarding his belief [when he was forced to convert]. There is a possibility that it [i.e., his forced conversion] was sincere, so he is to be killed as an apostate. It is [also] possible that he did not believe [in Islam while having been forced to convert] and then he [should] be a Dhimmi and shall not be killed."
--pp. 168 (Azharite)
"A female apostate is not to be killed [unlike the case of a male apostate]. She should be imprisoned and beaten every day until she becomes a Muslim [again]. It means that Islam should be offered to her and if she refuses it, she should be flogged. Then Islam should be offered to her [again] and if she refuses it, she should be imprisoned. And there is a version according to which she should be taken out every day and beaten as we have described, because it is not permissible to kill her. She has committed a gruesome crime that has no fixed punishment [hadd] for it, so she is punished by a non-fixed punishment [ta'zir], that is - beating and imprisonment."
--pp. 371 (Azharite)
And now, let's also see what the Koran has to say about forced conversions, shall we?
“Those who reject Faith,- neither their possessions nor their (numerous) progeny will avail them aught against God: they are themselves just fuel for the Fire.” -- Koran 3:10
“O you who believe, if you revert from your religion, then GOD will substitute in your place people whom He loves and who love Him. They will be kind with the believers, stern with the disbelievers, and will strive in the cause of GOD without fear of any blame. Such is GOD's blessing; He bestows it upon whomever He wills. GOD is Bounteous, Omniscient.” -- Koran 5:54
If you want to see many more quotes about how to fry an infidel who doesn't submit to Islam, please be my guest.