Wish I could advise regarding Tenggol, but I have not been there for over 20 years because I essentially stopped diving from 1996 to 2017. I'm now mostly diving abroad as it is quite easy to jump on a plane to Male or Denpasar.@CWK I frequently visit Malaysia as my other half is from Penang and I generally try to get a week away from the family to dive. In the past my daughter and I have been to Sipidan (actually I dived there a week after she was born in 1992), and Redang. Looking at Tengol and have been wondering if I should venture there next year. My daughter did a lot of shark research around Malaysia last year for FIN print but didn't recommend Tioman for me.
I did do some training on Tioman last year but would generally not recommend it for more experienced recreational divers. However, in terms of tec, you may wish to contact B&J. Darren (one of the tech instructors there) used to teach Padi and IANTD but I think he has recently dropped IANTD for TDI. You may be able to arrange some tec diving on WW II wrecks with him. See WWII Wrecks - B&J, Diving in Tioman