Currently I'm playing SkyFactory 2.4 on Aternos (loving the service), yet because veinminer is not a default mod of SF, it is not included. SkyFactory's grinding aspect is so much easier if you have veinminer, but I know you guys cannot have a modpack that is just adding veinminer. Although veinminer is an option for a mod, you are forced to install just that, meaning no modpack included. This is why I suggest there be a "Add" or "Install" button next to the already present "Reinstall" button. This would simply take the selected mod and add it to the mods folder. You could have a warning saying that incompatibility issues could arise if this button is pressed, and to proceed at your own risk.
Thanks,
Gymno