I hope you find this reply, I realize the post you made is 6 months old.
The way to get this to work is to make sure that when you download the m5stack_tinybasicplus.ino file you also have the TFT_Terminal.ino program in the same directory. the errors you are seeing are because the Arduino IDE apparently will include any .ino files that are in the project directory when it compiles.
I assume this is how it works, because at first I had the same error as you. I found the terminal .ino file in the same project, I opened it and realized that the code had the function termInit(); from the first error you mention, and I originally cut and pasted the code to get it to work.
I'm sorry no one replied. m5stack with the faces keyboard seems like it has some great potential but the documentation is so difficult to find and navigate it is really discouraging for beginners. I have been messing with SBCs and microcontrollers for about 5 years now and I still feel like a beginner. I hope the tutorials that I have seen in this forum help me learn more about this stuff.
Good luck and happy coding!