If WOLSLXO represents TRIVIAL, what does MNIFHK stand for?

Concept: In this word-based coding-decoding pattern, each letter of the code word (the string that 'represents' the answer) is converted into the corresponding letter of the decoded word by an alternating cyclic (Caesar-style) alphabet shift applied to the code letter — the shift amount keeps alternating between the same two values, e.g. -3, +3, -3, +3, ..., across consecutive letters, and the alphabet wraps around (after Z comes A again, and before A comes Z again).

Application: The image shows the code word WOLSLXO decoded into TRIVIAL by applying the alternating shifts -3, +3, -3, +3, -3, +3, -3 to each of its letters in turn. Using the same alternating pattern (starting again with -3) on the code word MNIFHK gives:

1. M (13th letter) shifts -3 to become J (10th letter).

2. N (14th letter) shifts +3 to become Q (17th letter).

3. I (9th letter) shifts -3 to become F (6th letter).

4. F (6th letter) shifts +3 to become I (9th letter).

5. H (8th letter) shifts -3 to become E (5th letter).

6. K (11th letter) shifts +3 to become N (14th letter).

Reading the shifted letters in order gives J, Q, F, I, E, N, i.e. JQFIEN — this is the word that MNIFHK stands for.

Cross-check: applying the reverse alternating shifts (+3, -3, +3, -3, +3, -3) to J, Q, F, I, E, N reproduces M, N, I, F, H, K exactly, confirming the mapping is consistent in both directions.