Hello and welcome to WeMod! 
There does seem to be a known issue with the infinite health cheat, as some have pointed out in the official thread for the trainer, here: Tomb Raider Cheats and Trainer for Steam.
The person who made the trainer is no longer with WeMod.
However, a member of staff might allow the option to vote for a new trainer to be made (https://support.wemod.com/article/43-how-do-i-request-an-update-for-games) by one of the current trainer makers here at WeMod. But honestly don’t get your hopes up for a new one any time soon, the game is nearly 7 years old, most of the game’s player-base has moved on.