The realization space is
  [1   0   1    1   0   1    0               1         -x2 + 2               1               1]
  [0   1   1   x1   0   0    1               1   -x1*x2 + 2*x1   -x1*x2 + 2*x1   -x1*x2 + 2*x1]
  [0   0   0    0   1   1   -1   -x1*x2 + 2*x1               1               1              x2]
in the multivariate polynomial ring in 2 variables over ZZ
within the vanishing set of the ideal
Ideal (x1^2*x2^2 - 3*x1^2*x2 + 2*x1^2 + x1*x2 - x2)
avoiding the zero loci of the polynomials
RingElem[x1, x2 - 2, x2 - 1, x1*x2 - 2*x1 + 1, x1*x2 - 2*x1 - x2 + 1, x1^2*x2^2 - 4*x1^2*x2 + 4*x1^2 + x1*x2 - 2*x1 - x2 + 1, x1^2*x2^2 - 4*x1^2*x2 + 4*x1^2 - x2, x1*x2 - 2*x1 + x2, x1*x2 - 2*x1 - x2, x1*x2 - x1 - x2, x2, x1 - 1, x1*x2 - 2*x1 - 1, x1*x2 - x1 - 1, x1*x2^2 - 4*x1*x2 + 4*x1 - 1, x1^2*x2 - 2*x1^2 + x1 - 1]