At another parish nearby, the priest always sits among the congregation (in the first row) during the readings before the Gospel ( instead of the presider’s chair). Is there a reason for this, and why haven’t I see this elsewhere? Has anyone else seen this?
It is irregular, at best.
I have not seen a reference directing that the priest celebrant to remain in the sanctuary while the readings are proclaimed. So, as a lay person, it would be very difficult for you to make a specific criticism on this point, particularly if you do not have a position of respect in regards to knowledge of liturgical matters.
However, there are a number of texts that allude to the fact that the priest should do just that: remain in the presider’s chair as the readings are being proclaimed:
GIRM 108.
One and the same priest celebrant must always exercise the presidential office in all of its parts, except for those parts which are proper to a Mass at which the Bishop is present
Instruction
Inter Oecumenici 92:* In relation to the plan of the church, the chair for the celebrant and ministers should occupy a place that is clearly visible to all the faithful and that makes it plain that the celebrant presides over the whole community.*
From those two paragraphs alone, it appears that the celebrant should remain in a presidential position throughout the liturgy. By abandoning the sanctuary and sitting with the congregants, it would appear that he is doing just that.
Another related point to this comes from GIRM 154:
The priest may give the sign of peace to the ministers but always remains within the sanctuary, so as not to disturb the celebration.
While this has to do with the sign of peace and not the readings, it is apparent from this that it is improper for the priest to leave the sanctuary.
You could look elsewhere in the GIRM to see that the ministers (both sacred and lay) are to have places within the sanctuary during the liturgy.
One word about the sanctuary:
GIRM 295. *The sanctuary is the place where the altar stands, where the word of God is proclaimed, and where the priest, the deacon, and the other ministers exercise their offices.
It should suitably be marked off from the body of the church either by its being somewhat elevated or by a particular structure and ornamentation. *
There is a theological reason for this: the people housed in the nave are supposed to be given a glimpse of the heavenly liturgy as shown in the Apocalypse. By having the sanctuary clearly delineated, this is more clearly delineated. (If you really want to see this, go to a Byzantine liturgy sometime. The iconostasis really sets it off well…makes me wish we’d go back to having Rood Screens in our Latin parishes) By having an excessive amount of traffic going in and out of the sanctuary during the liturgy, it reduces that significance and tends to lead people down the erroneous path of the Protestant belief in the Eucharist as a re-presentation of the Last Supper, rather than the re-presentation of the paschal sacrifice.