What counts as “one object” for the Illusion wizard’s Illusory Reality and Malleable Illusions features?

I DM for a player who is considering creating a School of Illusion Wizard. They have correctly noted that many things about illusions in the game are open to interpretation, and have asked me to let me know how I would rule on several interactions, in the interest of managing their own expectations. The following question asks about one of these interactions, with the intent of finding out if there is a definitive answer, and gathering information about what would be a reasonable/practical ruling that others have made at their tables if there isn’t.

The 14th-level School of Illusion wizard feature, Illusory Reality, can make one object in an illusion spell real for one minute (PHB, p. 118):

When you cast an illusion spell of 1st level or higher, you can choose one inanimate, nonmagical object that is part of the illusion and make that object real. You can do this on your turn as a bonus action while the spell is ongoing. The object remains real for 1 minute. For example, you can create an illusion of a bridge over a chasm and then make it real long enough for your allies to cross.

The object can’t deal damage or otherwise directly harm anyone.

Although the intent is that you can only use this feature on one object per illusion spell, this answer suggests you can use it multiple times on the same object while the spell persists.

But what exactly does “one object” mean, in the context of the 6th-level School of Illusion wizard feature, Malleable Illusions (PHB, p.118)?

Starting at 6th level, when you cast an illusion spell that has a duration of 1 minute or longer, you can use your action to change the nature of that illusion (using the spell’s normal parameters for the illusion), provided that you can see the illusion.

With Malleable Illusions, you can change an object in an illusion into another object, into a creature, or into something else (like graffiti on a wall).

This answer suggests that if you did so to an object made real with Illusory Reality, the changed object would remain real.

So: it seems like you might be able to make your “one object” real multiple times, while using Malleable Illusions to change it to a different object each time (if you can’t alter objects made real with Illusory Reality using Malleable Illusions, just wait until they are illusions again before using MI).

Is this actually possible?

(Obviously you would still only ever be able to have one real object per illusion spell at any particular time.)

As an example, consider this sequence of events:

  1. Create an illusory sword (with a spell such as Major Image)
  2. Make the sword real with Illusory Reality
  3. Wait a minute for the sword to become illusory again (whether you can apply Malleable Illusions to an object made real by Illusory Reality, and thus skip this step, is the subject of this question)
  4. Alter the nature of the illusory sword to be an illusory lump of coal instead
  5. Try to apply Illusory Reality to make the coal real. Can this be done?