In 1.12.2, when you install this mod on curseforge it will autoinstall the 1.16 version of iceberg because it's listed as a required dependency/library mod, but then it crashes because it's a 1.16 mod:)
I have logs if ya want em

Thanks for letting me know, this was likely an issue of CurseForge automatically assigning dependencies. I've removed Iceberg as a dependency for the latest 1.12 release. As of writing this, the CurseForge app is still automatically adding Iceberg when adding Legendary Tooltips, but I'm hoping within 24-48 hours they fix it. I'll close this issue but please reopen if it's still broken after a few days.
On a related note, it's really strange behavior that CurseForge installs a dependency version that it knows is wrong, I'll bring it up with support and see what they say.