You need a clear path to the point of origin for your spells.
Both thaumaturge and Minor Illusion target a point of origin for an effect area (in your range).
You must be able to target a specific point requiring a clear path, which you do not own because the wall provides full coverage (unless there are holes in that wall or some other way that provide you with a clear path), but you can place the point of origin of your side of the wall:
The targets (PHB 204):
A typical spell requires you to choose one or more targets to
affected by the magic of the spell. The description of a spell tells you if
the target spell of creatures, items, or a point of origin for an area
effect (described below).
A clear path to the target (PHB 204):
To target something, you must have a clear path, so it can not be
behind the total cover. If you place an effect area at a point that you
can not see and an obstacle, like a wall, is between you and this
point, the point of origin is on the near side of that