Repair concept: Brilliant idea or disaster in waiting?

Your humble opinions, please…
I put a subfloor in over a basement floor (using pre-fab tongue & groove panels). There were a few uneven parts that I shimmed. Since the carpet installation, I think one of the shims fell/broke/shifted and now there’s a part of the floor that dips down when you walk on it.

As luck would have it, I cut a heating vent sized hole in one of the panels to allow the concrete floor to breathe as per the subfloor maufacturers instructions, and this hole isn’t too far from the uneven part.

What I want to do is feed a flexible plastic tube down the hole, under the subfloor toward the dip then pour self-levelling concrete down the tube to fill the depression in the floor.

What do you think? Is RumMunkey’s basement about to be sturdy and level or is Mrs. Rum Munkey going to be pulling up concrete-encrusted carpet next week?

It would be better to lift a board or two in the affected area, securely repack and re-lay the boards.

There are ways to lift T&G boards from the middle of a floor; some details may be found here.