Using the term for anything where the source is JVM bytecode is plain wrong, and it's also dubious for anything targeting WebAssembly (though if the target is specifically .wat/.wast, it may perhaps be arguably defensible.)
so i guess one might use "transpile" wrt bytecode in the spirit of that. but i guess asm source files are still "human readable", where bytecode generally isn't considered as such.
[0] P47, "TRANS": http://www.patersontech.com/dos/Docs/86_Dos_usr_03.pdf
[1] http://www.s100computers.com/Software%20Folder/Assembler%20C...
I don't see why the existence of a grey area should be enough to question the utility of the term.
If compile/decompile are used for a transformations along one axis, transpile is used for transformations that are predominantly orthogonal to that axis.
Given the large inconsistency and incompatibility between all these definitions and the existence of a well-accepted term that comprises all of these definitions, is it a mystery why people question the utility of the term? After all, what use is a nuanced term if it can't reliably convey that additional information.
I would recommend the general term "A/B compiler" where A and B are arbitrary regular languages. That way it would be pretty clear what a Pascal/C compiler is, or a JVM/Webasm compiler, for instance. Or a x86/C compiler which would also make the word "decompiler" obsolete.
Just ask folks how this term differentiates from Compile and you'll get wildly varying answers and definitions.