New(?) Cavalry tactic/exploit

[caravel]

Does this tactic work, perhaps rather less dramatically, when infantry are doing the charging? E.g., FMAAs vs spears?

I'm unclear as to which tactic you're referring to, but if it's switching from hold formation to engage at will at the last moment to maintain a wider frontage to optimise "wrap around"(?) - then yes it works well, especially with swords vs spears (the bonus is a factor there). As ever this assumes you're using some reasonable tactics, e.g. not charging head on or uphill, etc...