Handle backup strings for second language

[chrisklus]

Because we are manually getting strings for the second language, like:

numberPlaySecondaryStrings[ `${NUMBER_PLAY_STRING_KEY_PREFIX}${stringKey}` ];

The sim crashes if the second language is missing a desired string key instead of gracefully filling in the English value like normal.

[chrisklus]

Adding blocks-sim-publication label to indicate this should be completed before starting dev testing

[pixelzoom]

@chrisklus I believe that I've addressed this in the above commit. Please review, close if OK.

[chrisklus]

@marlitas and I reviewed and made some changes in the above commits to support handling backup strings in number-compare as well, and then @pixelzoom @marlitas and I reviewed those changes together. I think we are set here, closing!