You should compare more carefully. There are 4 differences not 2.
Left aligned text:
(
(-1 . <Entity name: cb2deb0>)
(0 . "TEXT")
(5 . "AC")
(330 . <Entity name: caeb090>)
(100 . "AcDbEntity")
(67 . 0)
(410 . "Model")
(8 . "0")
(100 . "AcDbText")
(10 819.719 207.205 0.0)
(40 . 100.0)
(1 . "aaa")
(50 . 0.0)
(41 . 1.0)
(51 . 0.0)
(7 . "Standard")
(71 . 0)
(72 . 0)
(11 0.0 0.0 0.0)
(210 0.0 0.0 1.0)
(100 . "AcDbText")
(73 . 0)
)
Middle center aligned text:
(
(-1 . <Entity name: cbe0e38>)
(0 . "TEXT")
(5 . "AD")
(330 . <Entity name: caeb090>)
(100 . "AcDbEntity")
(67 . 0)
(410 . "Model")
(8 . "0")
(100 . "AcDbText")
(10 703.319 157.205 0.0) ; <-- First alignment point. Not the insertion point.
(40 . 100.0)
(1 . "aaa")
(50 . 0.0)
(41 . 1.0)
(51 . 0.0)
(7 . "Standard")
(71 . 0)
(72 . 1) ; <--
(11 819.719 207.205 0.0) ; <-- Second alignment point. Insertion point.
(210 0.0 0.0 1.0)
(100 . "AcDbText")
(73 . 2) ; <--
)
For the first alignment point of a middle center aligned text you can use a dummy point for the entmake(x) list. But gc 10 must be present. At least on BricsCAD this applies.