Is anything required of my wife for not completing Umrah after intending it and entering into ihram for it from Jeddah, due to the severe crowding in the Grand Mosque?

The state of ihram for Hajj or Umrah commences immediately upon forming the intention. Therefore, if your wife intended Umrah, she remains in her state of ihram and must abstain from its prohibitions. She must return to Makkah to complete her Umrah. Regarding the prohibitions she committed before exiting ihram:

For those that involve damage, such as cutting hair and trimming nails, there is one fidyah for each category (a sheep, or fasting for three days, or feeding six needy persons).

As for those that are for comfort, like wearing tailored clothes and using perfume, there is no penalty if she did them out of ignorance. Similarly, intercourse committed out of ignorance does not invalidate the Umrah.

If she is unable to return to Makkah, she is considered muhsarah (prevented). In this case, she must sacrifice a sheep to be distributed among the poor in her place of residence, or fast for ten days if she is unable to do so, and then exit ihram by shortening her hair.