Currently on Patchouli 1.1-22, Forge 28.1.102 for 1.14.4.
Attempting to put formatting inside a tooltip, e.g. $(t:$(o)foo)bar, yields foo)bar with $(o when hovered, as opposed to bar with foo when hovered.

Might I suggest doing $(o)$(t:foo)$()bar instead? This will add the italics, then tooltip, then end formatting, and display bar without tooltip or italics. There is nothing in the wiki that suggests tooltips can be nested, only lists $(li maybe.

This issue is stale because it has been open for a while with no activity. Please bump if this is still an issue, or this ticket will be closed soon.