Official GT's package name is gregtech and yours is gregtechmod.

I have no idea if thats by design but this is causing crashes with other mods.

That causes all addons like CropsPP to crash due to a ClassNotFoundException, which is totally reasonable since that class just doesn't exist, as far as both the GT addons and java are concerned.

List of addons that I could find that were affected

1 - ⚠️ ❌ CropsPP
Reproduction:

• Place any vanilla sapling into a IC2 Crop.
• Right Click at any stage of growth.

Code path:

// com.github.bartimaeusnek.cropspp.crops.cpp.Bonsais.java
@Override
public ItemStack getGain(ICropTile iCropTile) {
        int max = 0;
        for (int chanch : chanches) {
            max=Math.max(chanch,max);
        }
        // ClassNotFoundException: gregtech.api.objects.XSTR
        XSTR rand = new XSTR();
        
        int roll = rand.nextInt(max);
        for (int i = chanches.length - 1; i >= 0; i--) {

This one is specially worse, since the XSTR class doesn't exist on the project, so even if there were a way to redirect the call to your mod, it would fail.

It is of note that I was going to publish that on the Lost Era Modpack's Issue Tracker but since this a problem that involved a cross-mod compatibility issue that's more technical I've decided to put it here instead.

The package name of GT 4 was originally gregtechmod and you can check it at 1.6.4 version that been ported.
Seems addon is intended to work with GT5, not GT4.
Try reporting to addon dev tracker instead.