:The problem is a more general one.  All of the sources we have available today have been heavily filtered and diluted over time.  The Jain texts you refer to seem to have been written around (very roughly) the same time as the popular notion of the invention of the catapult in 399 BCE.  This makes them quite similar in time frame with the Biblical source describing a catapult.  In both cases, these are people writing down oral histories that had been passed down for some time.  Oral histories are subject to rapid change over time, but once written down, become (somewhat) stable. 
 :If you want my personal opinion, both the Jain texts and the Biblical text are solid sources in terms of catapults existing (and being common) at the time of the writings, but not so great as to how they pertain to the direct contents of the writing.  This is also good indications that the popular 399 BCE claim of invention (which I think was written much much later than that so in my opinion probably suffers from similar oral history issues) is probably not correct.  It seems likely that everyone was probably claiming for a period of a least a hundred years and maybe more that their particular king or hero or race or culture or god or whatever was the one that created these new machines of war.  I haven't looked at catapult research in a while.  I remember there are several other references available that hint that catapults might have existed as far back as 550 BCE, though as I recall there was not enough for any consensus.  There is even a claim of a picture of a catapult from 800ish BCE on a Nimrud relief, although the only images I've seen in relation to that claim look nothing at all like catapults. 
 :It's great that you have several sources.  However I'd suggest you make sure that these are not in fact all simply several people all repeating the opinion of secondary source.  This is how myths get created and perpetuated (e.g. "catapults were invented in 399 BCE").  If there is more than one person who has translated or interpreted the meaning of the Jain text that would be a big reassurance.  I see that happen all to often on other subjects I'm interested in.  If there are translations available of the text being referred to that would also be helpful. 
 :My favored approach for writing about such things (in general and on wikipedia) is to include lots of sources like the one you've added and the biblical source which has been asked for but not included, along with an honest discussion of what this might really mean.  It doesn't sound as clean as a plain statement like "catapults were invented in 399 BCE", but it would get across to the reader the honest fact that nobody is very sure or in very much agreement about exactly when catapults were invented or which culture might have been first. 
 :I should be clear that most of what I've said here is opinion and goes way above and beyond wikipedia rules.  I appreciate your contribution.  I just hope to make it clear that the interpretation of history this old is a very messy proposition.