How can a word for 'the act of Xing', semantically shift to mean 'the thing Xed'? [duplicate]

You are asking a question about the semantics of 15th-century legal English, and comparing it with your understanding of today’s English. It is fair to say that the explanation was not of the best.

Put simply, one common way of forming a noun from a verb derived from Latin is to add ‘*-ation *’ or ’-ition ‘ to the end. The resultant noun is used to refer to the doing of the the thing or the thing being done,. These two phrases are equivalent. The noun itself is neither active nor passive.

So a ‘consideration’ (apparently in the C15) was used (at least in a legal context) to refer to an outcome of an act of someone considering/something being considered: a reason. A possible course of action may have some considerations in its favour and others against it.

So, for example, The noun position is neither active nor passive. The position of the North Pole or Time Square has nothing to do with anybody putting them there. An exhibition involves both one or more exhibitors and some exhibitees, but an exhibition is the event - the show itself.

To consider is to reason or think. The derived noun spreads out widely.

A price/payment/bribe; thoughtfulness (what we do when we are considerate); something to ce taken into account (in deciding to agree to be married, one consideration might be compatibility of interests, another might the wealth or poverty of the partner concerned, etc...;

These are example. You can say that ‘consideration is both active and passive.

The considération of both sides of a dispute by a judge is the essence of justice.

The ‘of’ here seems to be trying to make ‘both sides’ the object of an underlying active verb, but the ‘by’ brings with it the flavour of passive. But the two adverbial prepositional phrases modify not a verb but a noun.