So I just skimmed through the text, because I pretty much know what is the issue here. SVG is a bit of a special format, which can be added to HTML in TWO main ways.
The simple way, is to add it into an <img src="path/to/file.svg">. However, in your case, since you have an interactive animated SVG, you have to add the actual <svg> code into the html (which is also what the browser can do when the file is accessed directly by URL):
So basically, for this specific interactive SVG, you can't just use <img src=""> which is what X3 can do when you drop the file into custom/logo. X3 can't read the SVG and generate the code for you, so this would have to be done manually.
I put this through Google AI, which explains it in detail. We are talking method 1 and 2, possibly 3.
https://share.google/aimode/228lln2TMLXmKheCJ
This isn't about what X3 specifically supports or not. If you try to embed your SVG file directly into any other HTML page yourself, it would also not render, unless you embed the actual <svg> code. It only works like that when you load the SVG file directly in browser, because it's not embedded.
I don't know how you created the SVG file, but ultimately the code for the SVG is the below, and this is what would need to be pasted into the html to display the entire interactive SVG. Keep in mind, you have also assigned width/height attributes here, which may need to be considered, unless you use CSS to override.
<svg xmlns="http://www.w3.org/2000/svg" viewBox="32 -238 2011 1055" width="800" height="410">
<image href="https://x3.NitroWings.me/content/custom/logo/logos_image_folder/US_Navy_030130-N-0226M-002_P-3C_Orion~cropped-40px~tail-fixed_inPixio12.png" x="0" y="0" width="2068" height="547" transform="rotate(0 1034 273.5)">
<animateTransform attributeName="transform" attributeType="XML" type="rotate" values="-30 1034 273.5; -30 1034 273.5; 30 1034 273.5; 30 1034 273.5; -30 1034 273.5" keyTimes="0; .01923; .5; .51923; 1" dur="13s" repeatCount="indefinite" calcMode="spline" keySplines=".42 0 .58 1; .42 0 .58 1; .42 0 .58 1; .42 0 .58 1"/>
</image>
</svg>
I think what you may need to consider here, is that your SVG isn't really just a picture, but an encapsulated interactive presentation, which can't display inside the simple <img> tag.
