This topic causes a lot of grief on here though. It might be a classic case where the technical/defined definition has diverged from the vernacular. In a sense both are right.
I believe a transpiler is especially for source-to-source translations where the source and target have the same abstraction level. For example, Python's tool 2to3 could be called a transpiler.
Therefore, you would not use the term "transpiler" for something like Typescript to LLVM IR (if it exists).
One person’s formal thing is another person’s buzzword.
I would point to the word ‘Soliton’ in physics which is used for two different things.