I'm using terraqueous 1.3.6 for 1.11.0/2 and I broke lemon tree wood and got mango tree wood. I was using an axe with silk touch. Not sure if it was the enchantment or if it is broken that way.
[EDIT] It is the enchantment because I broke a peach tree with the enchantment and got apple wood. Without I got peach. So breaking a tree with an axe with the Silk Touch enchantment cause it to change trees. Please fix.