aeneas is a tool used to synchronize audio and text. It takes an audio file and a list of phrases as inputs. Its output is a synchronization timing file. The way aeneas works is to synthesize each phrase using a text-to-speech engine, and then compare the synthesized audio files against the input audio file to find the phrase breaks.
aeneas must be installed if you will use the aeneas to adjust timings. If it is not installed, a warning appears when you use it to set timings.
To get aeneas, see: https://bloomlibrary.org/aeneas.
If you do not install aeneas, Bloom will continue to use pause-based timing.