The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  X  X  1  1  1  X  0  2  X
 0  X  0  0  0  0  0  0  0  X X+2  X  2  X  2  X X+2 X+2  X  X X+2
 0  0  X  0  0  0  X X+2  X  X  X  0  X  2  0  2  X  X  2  0  X
 0  0  0  X  0  X  X  X  2  0  0  2  X  0  2 X+2  2 X+2  0  X X+2
 0  0  0  0  X  X  2 X+2 X+2  0  X  X  X X+2 X+2  X  X  0  0  0  2
 0  0  0  0  0  2  2  2  2  2  0  0  0  2  2  2  2  0  2  2  0

generates a code of length 21 over Z4[X]/(X^2+2,2X) who´s minimum homogenous weight is 15.

Homogenous weight enumerator: w(x)=1x^0+64x^15+146x^16+172x^17+262x^18+404x^19+624x^20+744x^21+602x^22+456x^23+292x^24+156x^25+90x^26+36x^27+24x^28+16x^29+6x^30+1x^32

The gray image is a code over GF(2) with n=84, k=12 and d=30.
This code was found by Heurico 1.16 in 1.28 seconds.