To be honest, I found a lot more information about getting rid of Box Elder than I did about supporting its growth and health. It is a native tree and is a provides food and shelter for pollinators, birds and some mammals and it is of value in that sense. So, I am going to start with the advice I follow for every serious tree problem and which I suggest to everyone who needs help with a tree problem:

The absolute best advice for every serious tree problem is to consult an ISA certified arborist. Many tree companies offer advice but are not certified. Look for the extra education and training that comes with the certification.

Here is a link to an excellent fact sheet from Ohio State with tips about finding and hiring an arborist:

https://ohioline.osu.edu/factsheet/hyg-1032

And this is a link to finding a certified arborist in your area by using your zip code:

https://www.treesaregood.org/findanarborist/findanarborist

Now then, as for box elders in particular. Their scientific name is Acer negundo. All maple trees are in the Acer genus so they are, in fact, a Maple tree. They are actually the most common of all the Maple trees. They are sometimes called the Ashleaf maple. That does not definitely mean that your silver maples will “catch” whatever is bothering the box elder but it certainly is a possibility.

Please read through the articles found in the links below. They contain some of the information I found about box elders:

Boxelder | Texas Plant Disease Handbook (tamu.edu)

D:\PROGRAM FILES\SOFTQUAD\HOTMETAL PRO 4\gifs\acerneg0.htm (usda.gov)

Acer negundo (Ash-Leaf Maple, Ashleaf maple, Boxelder, Box elder) | North Carolina Extension Gardener Plant Toolbox (ncsu.edu)

The most common problem for box elders seems to be the box elder bug, which really isn’t a problem at all for a healthy tree. They just chew up some leaves and want to come in your house but it isn’t something that will cause what you’re seeing. Foliar diseases are common but do not usually cause damage that threatens the overall health of the tree.

The USDA information sheet (center link, above) states the following:

A red stain in the wood of living trees caused by Fusarium reticulatum var. negundinis apparently is specific to boxelder. The stain regularly is associated with Cerambycid beetles and the galleries of other insects, but itself does no damage to the wood (14).

Several of the fact sheets mention the Asian Ambrosia beetle which can damage box elders. Their chewing could also provide entry for fungal pathogens which could conceivably cause the wounds you are seeing.

However, I am just not finding anything which positively identifies the type of injury seen in your pictures and, therefore, I cannot suggest a course of action to alleviate the problem. Again, the best way to deal with a serious tree problem is to find and consult with an ISA certified arborist. Their services are generally much less expensive than that of replacing a tree. I’m sorry that I cannot give you a more specific answer. Thank you for your patience as this research took some extra time.