i dont think the cert refers to the # 900 ...
this is what he claims i have heard him say on video "i am master of 900 form"
i think that a good number of the 900 forms we given to him in 1992 from a peer of ie chang ming in indonisia, i could be mistaken.
i am sure sin kwang the claims no authority over any shaolin monk or any temple.
i do not know if i have heard him say he is the only grandmaster of shaolin. i have heard many sd students express that opinion.
i think there are many people who can truly claim the title. i have heard of a few current traditional shaolin monks who practice 400 or more forms i posted a thread about one of them last year after reading about it in kung fu magazine.
sd does have a larger set of material than any system i know of. so i dont know if that claim is off or not.
i really can comment much on the legends about su kong tai jin, even sin kwang the would have to take another mans word about that.
the history/facts of exactly how all the material was introduced to ie chang ming is unknown to me.
i hope these comments shed a little light and cause you to ask more questions.
it is a very unclear history so i try to only talk about things i think are true.
best,
bruce