If consciousness is a Reification, how does a Buddha attain the Truth?

The question make a wrong comparison. It's a totally different story.

From question's quote, ven. Sāriputta in Ma. Mū. Mahāvedallasuttaṃ (MN 43) is talking about minds&wisdoms, which are clinging-aggregates of run-of-the-mill person before enlightenment; But from question's asking, enlightened minds&wisdoms of Buddha are minds&wisdoms after enlightenment, so Buddha's enlightenment-wisdoms are declung-aggregates of the noble one.

1. Question's quote is declung-aggregates:

Declung-aggregates in Sutta. Saṃ. Sa. issatthasuttaṃ:

The entire spectrum of an adept’s ethic-aggregate, immersion-aggregate, wisdom-aggregate, freedom-aggregate, and knowledge&vision-aggregate of freedom.

Asekkhena sīlakkhandhena samannāgato hoti, asekkhena samādhikkhandhena samannāgato hoti, asekkhena paññākkhandhena samannāgato hoti, asekkhena vimuttikkhandhena samannāgato hoti, asekkhena vimuttiñāṇadassanakkhandhena samannāgato hoti.

Declung-mind-aggregates in the end of Sutta. Saṃ. Kha. Anattalakkhaṇasutta:

And while this exposition was being given, the cittas of the group of five bhikkhus, by not clinging, were liberated from the āsavas.

Imasmiñ·ca pana veyyākaraṇasmiṃ bhaññamāne pañca·vaggiyānaṃ bhikkhūnaṃ anupādāya āsavehi cittāni vimucciṃsūti.

Declung-wisdom-aggregates and declung-mind-aggregates in Sutta. Ma. U. Mahācattārīsakasuttaṃ:

“And what, bhikkhus, is right view that is noble, taintless, supramundane, a factor of the path? The wisdom(paññā), the faculty of wisdom, the power of wisdom, the investigation-of-states enlightenment factor, the path factor of right view in one whose mind(citta) is noble, whose mind(citta) is taintless, who possesses the noble path and is developing the noble path: this is right view that is noble, taintless, supramundane, a factor of the path.

2. But question asking about clinging-aggregates:

Clinging-wisdom-aggregates in Sutta. Ma. U. Mahācattārīsakasuttaṃ:

“And what, bhikkhus, is right view that is affected by the taints, partaking of merit, ripening in the acquisitions? ‘There is what is given and what is offered and what is sacrificed; there is fruit and result of good and bad actions; there is this world and the other world; there is mother and father; there are beings who are reborn spontaneously; there are in the world good and virtuous recluses and brahmins who have realised for themselves by direct knowledge and declare this world and the other world.’ This is right view affected by taints, partaking of merit, ripening in the acquisitions.

Clinging-mind-aggregates in Sutta. Tī. Ma. Mahāsatipaṭṭhānasuttaṃ Cittānupassanāpabba:

Here, bhikkhus, a bhikkhu understands citta with rāga as "citta with rāga", or he understands citta without rāga as "citta without rāga", or he understands citta with dosa as "citta with dosa", or he understands citta without dosa as "citta without dosa", or he understands citta with moha as "citta with moha", or he understands citta without moha as "citta without moha", ...

So, the Enlightenment or Wisdom of a Buddha is a Reification, and the other aggregates as well.

Note: Citta (mind), mano (intellect), and viññāna (experience/consciousness) are same, according to Sutta. Saṃ. Ni. assutavasutta:

"But as for what's called 'mind,' 'intellect,' or 'consciousness,' the uninstructed run-of-the-mill person is unable to grow disenchanted with it, unable to grow dispassionate toward it, unable to gain release from it...

The Buddha attains the Truth through cessation of reification.

Reification is an important concept in (modern) Mahayana Buddhism. It refers to (samsaric) mind's tendency to assume something to be concrete and solid when in fact it's not. Reification is the opposite of the correct vision of Shunyata - the non-concrete nature of all phenomena.

Most if not all real life instances of Desire/Aversion/Confusion can be traced back to reification. One type of scenarios that can be explained in terms of reification is reading-in a concrete meaning into an abstract concept, and then applying that assumed meaning back to reality thereby overgeneralizing the observations. Some random examples that come to mind:

• Assuming that "democracy" refers to some concrete ideology when in fact there is no single specific definition of it, and then passing judgements about people based on that assumption.
• Fabricating an image of what "real love" must look like and then seeking to find it exactly like that in the real world.
• Assuming that Enlightenment or Nirvana refers to some concrete state that can be achieved "with a click".
• Side taking in any social conflict based on a generalized ideological position.

Another class of reification scenarios do not start from a concept, but rather come from subconscious assigning of ontological status to one's own observations:

• Overgeneralizing a person's physical appearance as "handsome" based on several characteristics that the observer finds matching one's preconception of beauty. Or even worse, finding those characteristics beautiful because they are assumed to be outward manifestations of inner qualities that the observer considers "good".
• Solidifying the notions of "stupid" and "smart" as something concrete and then judging a person as one or the other based on very little evidence interpreted as "a sure mark".
• Ego as a sum-total of one's opinions about oneself, one's social image, one's values and beliefs, one's job and role - coalesced and generalized into a solid notion of "this is who I am".

(I will add more examples as I remember them)

In a way, all our (samsaric) experience is reification. The process of perceiving objects, events, places, space, time, arising and destruction of entities - is a process of constructing fabrications from observations and reifying them as something concrete and separate from everything else and from the observer.

The Buddha attains the Truth through cessation of reification.