const imageDoc = parser.parseFromString(imageSvgContent, "image/svg+xml");
const imageRoot = imageDoc.documentElement;

let scaleX = 1;
let scaleY = 1;
let origWidth = 0;
let origHeight = 0;
let viewBoxX = 0;
let viewBoxY = 0;

if (img.width && img.height) {
    const origWidthAttr = imageRoot.getAttribute("width");
    const origHeightAttr = imageRoot.getAttribute("height");
    if (origWidthAttr && origHeightAttr) {
        origWidth = parseFloat(origWidthAttr);
        origHeight = parseFloat(origHeightAttr);
    }
    if (!origWidth || !origHeight) {
        const viewBox = imageRoot.getAttribute("viewBox");
        if (viewBox) {
            const parts = viewBox.split(/\s+|,/);
            if (parts.length === 4) {
                viewBoxX = parseFloat(parts[0]);
                viewBoxY = parseFloat(parts[1]);
                origWidth = parseFloat(parts[2]);
                origHeight = parseFloat(parts[3]);
            }
        }
    }
    if (origWidth && origHeight) {
        scaleX = img.width / origWidth;
        scaleY = img.height / origHeight;
    }

    const translateX = (img.x ?? 0) - viewBoxX * scaleX;
    const translateY = (img.y ?? 0) - viewBoxY * scaleY;
    console.log(viewBoxX, viewBoxY)

    const g = doc.createElementNS("http://www.w3.org/2000/svg", "g");
    g.setAttribute(
        "transform",
        `translate(${translateX}, ${translateY}) scale(${scaleX}, ${scaleY})`
    );

    Array.from(imageRoot.childNodes).forEach((child) => {
        g.appendChild(doc.importNode(child, true));
    });

    additionalGroup.appendChild(g);
}

doc.documentElement.appendChild(additionalGroup);

...