Return to Answer

(>r)*3 (swap r>)*3 (dup >r) (swap >r)*3 (>r)*3

(>r)*3 (r> swap)*3 (dup >r) (swap >r)*3 (r>)*3

iⱮ’“¡©“®¢‘xⱮj€12b4;,a"4,1ɗF - Link: starting (reversed); final (reversed)
 Ɱ                          - map with:
i                           -   first index of (final item) in (starting items)
  ’                         - decrement
   “¡©“®¢‘                  - code-page indices = [[0,6],[8,1]]
           Ɱ                - map with:
          x                 -   times - e.g. 3 -> [[0,0,0,6,6,6],[8,8,8,1,1,1]]
            j€12            - join each with twelves
                b4          - convert from base four
                                0->[0]; 6->[1,2]; 12->[3,0]; 8->[2,0]; 1->[1]
                         ɗ  - last three links as a dyad - f(starting, final):
                   ,        -   pair -> [starting, final] e.g. ["abc","ba"]
                      4,1   -   [4,1]                          [4,1]
                     "      -   zip with:
                    a       -     logical AND                  [[4,4,4],[1,1]]
                  ;         - concatenate
                          F - flatten

iⱮ’“¡©“®¢‘xⱮj€12b4;,a"4,1ɗF - Link: starting (reversed); final (reversed)
 Ɱ                          - map with:
i                           -   first index of (final item) in (starting items)
  ’                         - decrement -> 0-based indices
   “¡©“®¢‘                  - code-page indices = [[0,6],[8,1]]
           Ɱ                - map with:
          x                 -   times - e.g. 3 -> [[0,0,0,6,6,6],[8,8,8,1,1,1]]
            j€12            - join each with twelves
                b4          - convert from base four
                                0->[0]; 6->[1,2]; 12->[3,0]; 8->[2,0]; 1->[1]
                         ɗ  - last three links as a dyad - f(starting, final):
                   ,        -   pair -> [starting, final] e.g. ["abc","ba"]
                      4,1   -   [4,1]                          [4,1]
                     "      -   zip with:
                    a       -     logical AND                  [[4,4,4],[1,1]]
                  ;         - concatenate
                          F - flatten

^{26 if the result need not be flat (while still consistent) - remove trailing F}

Code breakdown

iⱮ’“¡©“®¢‘xⱮj€12b4;,a"4,1ɗF - Link: starting (reversed); final (reversed)
 Ɱ                          - map with:
i                           -   first index of (final item) in (starting items)
  ’                         - decrement
   “¡©“®¢‘                  - code-page indices = [[0,6],[8,1]]
           Ɱ                - map with:
          x                 -   times - e.g. 3 -> [[0,0,0,6,6,6],[8,8,8,1,1,1]]
            j€12            - join each with twelves
                b4          - convert from base four
                                0->[0]; 6->[1,2]; 12->[3,0]; 8->[2,0]; 1->[1]
                         ɗ  - last three links as a dyad - f(starting, final):
                   ,        -   pair -> [starting, final] e.g. ["abc","ba"]
                      4,1   -   [4,1]                          [4,1]
                     "      -   zip with:
                    a       -     logical AND                  [[4,4,4],[1,1]]
                  ;         - concatenate
                          F - flatten