Is being conscious of actions' consequences enough to attain nibbana?

There are three levels you have to be conscious of: - latent - transgression - Manifestation

It appears you are conscious only of the manifestation level. Only by practicing Satipathana you can tap to the other two levels.

Root condition. Buddhist training is directed towards eliminating the defilements (kilesaa). The foremost defilements are the three unwholesome roots — greed, hate, and delusion. From these spring others: conceit (maana), speculative views (di.t.thi), skeptical doubt (vicikicchaa), mental torpor (thiina), restlessness (uddhacca), shamelessness (ahirika), lack of moral fear or conscience (anottappa). These defilements function at three levels:

Transgression (viitikkama) leading to evil bodily and verbal acts. This is checked by the practice of morality, observing the five precepts. Obsession (pariyu.t.thaana) when the defilements come to the conscious level and threaten to lead to transgression if not restrained by the practice of mindfulness. Latency (anusaya) where they remain as tendencies ready to surface through the impact of sensory stimuli. Security from the defilements can be obtained only by destroying the three roots — greed, hate and delusion — at the level of latency. This requires insight-wisdom (vipassanaa-paññaa), the decisive liberating factor in Buddhism.

https://www.accesstoinsight.org/lib/authors/mendis/wheel322.html

Conscious of what? You have to delineate what you mean by conscious.

One can have eye consciousness and can see, but he/she could be deluded and get attached to beautiful things or could be averse to ugly sights.

However, If one is conscious of the three marks of existence on everything then that person is wise and free from suffering..

Once nibbana gets realized ,everything becomes possible ,wholesome unwholsome ,concious un conscious ,all life is embraced,with all its colors ,just a total surrender to whatever the case,even to not surrendering.

Being conscious is just a tool,and yes it can be enough ,but once you realize nibbana ,the tool doesn't have to be a concern anymore.When you say

"I just thought someone who is fully aware of their thoughts and actions will only work towards a joyful life. If someone does anything that leads to sorrow, I think it's only due to lack of consciousness of it's consequences."

that is a valid observation ,thats why the tool is effective.However as I said once the realization occurs , nobody needs to stay concious all the time to maintain nibbana.

Can someone consciously do unwholesome deeds?

Pick your definitions of "consciously" and "unwholesome".

Somebody might believe, for example ...

• I'll be happier when I marry
• I'll be happier if I behave in a way that's admired by this group of friends, in order to fit into that group
• It's better to be rich
• It good to punish anyone who hurts me
• It's better to be superior

... I think these are all examples of conventional or normal beliefs, which are more-or-less common in society.

People might consciously as well as unconsciously believe them -- i.e. they might be "a view".

Maybe that's why Buddhism emphasises "right view" as an important prerequisite -- or even, before that, right morality.

It seems to me you are defining consciousness as "being fully aware of consequences" and therefore "acting towards a better state", correct? (Just so you know, usually this is called "acting with virtue".)

If this is how you define it, then yes - acting with virtue is enough for Nibbana. The cool thing about acting with virtue is, the more you do it, the more it changes your life in the direction of Nibbana, the easier it gets to act even more virtuously. In fact, clearly understanding this self-fulfilling principle is exactly what's called Stream Entry.

The only other factor you need for Nibbana is to always keep improving your virtue, always looking for ways to make it more sublime and more refined. For this, you need to be 100% honest with yourself, even critical.

Taken together, these two factors - Acting with Virtue and Continuous Improvement - will create the right cyclic engine to propel a sentient being to more and more sublime forms of happiness until complete Nibbana.

No. It won't.

Right Mindfulness is the seventh stage of the Noble Eightfold Path. The eighth step is Right Immersion. Immersion provides the insight and wisdom that informs Right View.

SN12.23:2.13: I say that truly knowing and seeing has a vital condition. And what is it? You should say: ‘Immersion.’

The Noble Eightfold Path is conditioned. This means that eventual success is obtained in some life at some point for stream-enterers. However, since rebirth in a life conducive to practice is quite rare, it would be best to embrace the entire path sooner rather than later.

Please also practice Right Immersion in this very life.