YOU SAID:

the trophy would not fit into the brown suitcase because the yellow suitcase would not fit into the brown trophy

INTO JAPANESE

黄色のスーツケースが茶色のトロフィーに収まらないため、トロフィーは茶色のスーツケースに収まりません

BACK INTO ENGLISH

The trophy doesn't fit in the brown suitcase because the yellow suitcase doesn't fit in the brown trophy

INTO JAPANESE

黄色のスーツケースが茶色のトロフィーに収まらないため、トロフィーが茶色のスーツケースに収まらない

BACK INTO ENGLISH

The trophy doesn't fit in the brown suitcase because the yellow suitcase doesn't fit in the brown trophy