There's a lot of forge world units that mysteriously didn't get rules updates, at least for orks.
And while there will almost certainly be a codex: imperial knights, it will almost certainly NOT include forge world models.
As to when FW will update their rules - the answer is, as ever, 'maybe, if they feel like it'.
Probably the best hope for such forgotten units is an update via the warhammer community, but who knows when/if that will happen.
In the meantime, proxy them as something else.
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