If you start Tekkit Legends in offlinemode the Game carshs but if you disable
'B:useTechnicIcon' in the config the game do not crash...
Here you have the crash report...

crash-2018-04-10_23.02.58-client.txt

Unable to reproduce in Tekkit Legends 1.1.1 with the same itlt 0.0.8 version. Updating to itlt 1.0.2 might help though.

If you still encounter problems after updating itlt to 1.0.2, please comment here and I'll reopen this.