Most of the items are marked in the code as well, with full explanation.
grep for TODO and ugh/ugr/urg
+
+ * decimal point in \paper {}
+
> I have changed Mark_engraver to use the G_... classes.
> My implementation has the following shortcomings at the
> moment.
* fix: cello suites
- * fix: text on rests: rediculous dims
+ * fix: petites preludes (rediculous dims)
* fix extender
* gallina barlines.
* fix height of / collisions with lyrics (chords),
- see input/test/vertical-text.ly; input/test/repeat.ly
+ see input/test/vertical-text.ly
* repeat/volta:
- one volta spanner per score