Hello Christian,
It is spelled as “gati” even though pronounced “gathi.”
For Āsava, see, “4 results for āsavasutta”
There are many suttas that discuss those. “11090 results for gati and āsava”
– Some of them may not be relevant, but you can probably find some there.
Also note the convention adopted to write “Tipitaka English”: ““Tipiṭaka English” Convention Adopted by Early European Scholars – Part 1”
– Otherwise, the words will be too long.
– That is why “gathi” is written as “gati.”