Could a standardized ternary system be more efficient than the binary system?
Whether this is more efficient depends on the physical properties of the medium, not on any fundamental principle of computer science.  And of course there's no reason to limit yourself to ternary systems; we can consider systems with $k$ levels, where $k$ is any integer with $k \ge 2$ (it doesn't have to be limited to $k=2$ or $k=3$).

For instance, Wifi apparently uses BSK (a binary system, $k=2$), QPSK (a quad-level system, $k=4$), 16-QAM (a 16-level system), or 64-QAM (a 64-level system).
Cable TV apparently uses 64-QAM and 256-QAM, which is a modulation scheme that uses $k=64$ or $k=256$ different levels.  Why?  Because this is more efficient than using a binary ($k=2$) system.  There are many other examples like this in the communications world.

On the other hand, digital circuits -- as typically used in a CPU -- seem to be most effective with two-level modulation (i.e., binary, $k=2$).  Why?  The physics are different.

So, yes, sometimes this is more efficient, and sometimes it is not.  It all depends on the specific properties of the hardware you're working with.  Those properties are a matter of electrical engineering and physics, rather than of computer science.

There's lots more on this subject at Ternary processing instead of Binary, Why Do Computers Use the Binary Number System (0,1)?, and Could computer architecture be reworked to support switching from binary to ternary, for example?, for starters.