Insightful stuff, Johnathan.So to explain the sample above, and how it is pertinent to fix the OP's first display.
The first picture is the original display.
The Main tree is a Black Pine 黒松 in a Moyougi 模様木 (informal upright) styling on a Rosewood midsize table.
The accent is a Himeshara 姫しゃら in a Kabudachi 株立ち styling on an irregular shaped informal slab (Sou no Sou).
The scroll is the image of a Nightingale 鶯 perched on bamboo.
The revised display by the Sensei is the lower picture.
The Black Pine and display are unchanged.
The accent is changed to a Plum (梅)that is just beginning to bloom in a literati (informal) slab on a round, finished rosewood slab.
The scroll is changed to a traveling monk with an alms bowl.
Important points regarding the changes. If you have not learned about the Shin 真, Gyou 行, Sou 草 system of formality in Japanese art esthetics some of the explanations may be difficult to comprehend. The formal species (Black Pine) with the formal styling (Moyougi) sets the tone for the entire display. Yes, I know in English we call Moyougi styling Informal upright, but it is mostly considered a formal bonsai style in Japan. The Himeshara in an informal style placed upon an informal slab is technically correct. However, the size of the tree and slab compared to the size of the main tree and slab causes too much competition and not enough harmony between the two pieces. Additionally the Himeshara in bloom is already an indicator of Spring seasonality and the Uguisu is redundant to indicate seasonality.
Changing to the Plum, decreases the size of the accent so that it no longer competes with the main tree. Additionally changing the slab to have a slightly more formal (technically this would be a Sou no Shin) jiita, helps to harmonize with the main tree and stand. The Ume in blossom also denotes the seasonality of the season, hence the removal of the Nightingale to not have redundant themes. Monk indicating Heaven.
Now...how does this relate to the OP's display.
The most glaring problem with the display to me is not being able to determine the main tree and the lack of harmony between the two. They are both main pieces in this context. Secondly, some have stated they feel the scroll is too large...but this is not my problem with the scroll. The field maple in the Cascade style is beautiful on that stand. But as another poster already mentioned this indicates elevation on a mountain. The picture in the scroll is distant mountains, and is a redundant theme in the display. Shooting for a winter display, I would keep only the field maple if the field maple can grow in elevated mountains, and put a scene in the scroll such as rabbit tracks in the snow, or a fox on the prowl...No other accent would be needed.
When contemplating the OP’s display elements, I found the two trees really don’t complement each other, rather, they tend to compete with each other instead. Both are nice trees, but I think different companions would suit them better.