I literally don't know how to break it down to you guys more simply than this but the fundamental essence of a colony failure at its most basic level is in, well, the colony failing to appear in the first place. There are real world examples of this, even. The literal existence of the United Kingdom as a thing came about as the result of a colony failure that was the result of, in metatheurgist's words, "the builders failing to fill the contract" and indeed in the case of the Darien Scheme, the colony never existed before the failure of it bankrupted Scotland and forced them into signing the Acts of Union.
All of that flowery language deleteduser wrote down is literally what I'm talking about when you take away the prose and examine the content, you realize all of those reasons are what caused the Darien colony to fail too. What could possibly be more exemplary of ignorance, incompetence, indifference, and the triumph of ego over obligation than sending a bunch of pale, pasty Scotsmen to Central America to try and make a colony in PANAMA in 1690?
The path of a new Colony is certainly filled with obstacles.
Not getting off the drawing board due to a lack of interest/resources is certainly one way a Colony can fail.
But rather a moot point.
Having filled ships with and then landed millions of settlers on distant shores, there are yet more obstacles for Colonies to overcome...
If an Architect has no objective other than to erect a staging post for further expansion, so designs a Colony with zero regard to long-term viability, or...
If an earnest Architect's designs failed to account for the realities of the system they've colonised, planning to establish one type of economic endeavour, while the system is only suited to a different type.... as a couple of for instances.
As for Darien...
Settlers made landfall late in 1698
The Colony was abandoned by the settlers early in 1700
Over a year between establishment and abandonment.
We are mere
weeks into to this new program of expansion. In the timeframe that the few hundred settlers of Darien were barely half way across the Atlantic ocean, the Architects have ferried billions of souls, hundreds of billions of tons of resources and completed initial constructions in thousands of systems, LYs from their nearest neighbours. Yet already we hear Architects lack of committment, bemoaning their lack of understanding or the viscitudes of the powers that be... and their own consequent inadequate planning for Colonies they've established.