IS claims Ansbach attacker was a member for years

A few hours ago, IS'S al-Naba newspaper published a one-page profile of the man who committed a suicide attack in Ansbach in Germany a couple of days ago. Here are the points that I find most interesting. (And this is all according to al-Naba and the IS. Nothing of this has been verified yet!)

* The man's name is given as Abu Jusuf al-Karrar, which sounds like a Kunya to me. 
* He is said to have fought as a "Mujahid" from the very start of the Syrian civil war
* In particular, he is said to have formed a cell specialized in grenade and molotov cocktail attacks on the regime
* He is reported to have worked / fought with several groups before joining the IS 
* Around the time of the split between Jabat al-Nusra and IS, he was wounded in or near Aleppo and was brought out of the country for treatment
* Next, he is placed in Europe by al-Naba, from where, they say, he unsuccessfully tried to rejoin the Syrian battlefield and the IS several times
* Because he didn't manage to get back to Syria, he then decided to perpetrate an attack in Germany
* He is reported to have first placed with the idea of attacking cars
* Then he started to build his explosive device, in which, Al-Naba says, he spent 3 months
* During this period allegedly German police raided the "Makan", which I would read as the place where he lived, so rather the facility than his particular room. In any case, they didn't detect his plans. 
* A day before the attack, he is said to have done reconaisance of the location
* He is also said to have been in constant touch with "one of the soldiers" of the IS. 

Al-Naba's issue featuring the Ansbach attacker
If the basic facts check out, this would point to the attacker not having been a refugee who radicalized after coming to Europe but to having been a dyed-in-the-wool jihadist who hid is intentions and beliefs. 

If it is furthermore true that he was in direct touch with the IS, the question will arise why that was never detected. (I know that is difficult, but the question will arise nonetheless.) 

If the basic story checks out, it would also mean that the Ansbach attacker would have to be placed somewhere between what we already have learnt are different prototypes of IS-inspired or -directed attackers in the West: He would not have been sent here with orders to disguise himself as a refugee in order to perpetrate an attack like some of the Paris plotters and attackers. But he would also be different from, e.g. the Wuerzburg attacker, who for all we know radicalized here. 

Some of the claims, I am confident, the security services will be able to check out and then we will know more. It is likely that the IS exaggerates some aspects. It is in my opinion also unlikely, however, that the IS completely fabricates a story like this.