I didn't see any changes on the IMM5406.
It seems that 5406 was eventually changed. It has been re-arranged significantly, and now requires email addresses for everybody on the form, instead of the select few on the old form. Birthplace has now been clarified as Country of Birth, and a pull-down now allows one to enter "married, physically present" which was previously impossible.
Also, I'm not sure when this happened, but the checklist, IMM5533e has undergone further changes since the Feb 14th announcement. (I captured both of the new forms on the evening of the 14th, and again on the 27th - and both had changed again.)
The version that I retrieved last night appears to be faulty. On page 4, question 3, there are stray check boxes labelled Yes and No with no corresponding question. Then, on page 5, question 4, the previous common-law question has no place to answer. Presumably the stray checkboxes on the previous page pertain to this.
Has anybody else noticed this ? I suppose it could be some obscure Adobe bug, but it seems more likely to be a broken form.