It's important to delineate between tariffs and currency manipulation... the tariffs mentioned in the article will hurt US businesses by taxing their goods in China while hurting Chinese consumers by taxing the goods they buy from the US. Of course, it will benefit Chinese automakers, but it will hurt the Chinese economy more than it will help, since the resources allocated to the increased domestic production of autos would have been more efficiently used elsewhere in the economy.
Regarding trade deficits in general and currency manipulation in particular:
The balance of trade is a small part of what comprises the balance of payments. The BOP always has to equal zero, in other words money flowing out of a country = money flowing into a country. This is because if you have more money flowing out of a country, then the prices in that country become depressed due to less money while the prices in other countries become inflated due to more money, which then encourages a reversal in the flow of money (obviously money will flow to where the lowest prices are).
Another way to look at it is: If the US buys $100 worth of goods from China, the Chinese have $100 in dollar bills that are useless in their country. What they can do with it is either spend it on $100 worth of US goods, thereby leading to a trade balance of zero, or spend it on $100 worth of US assets. If they spend it on $100 worth of US assets, like government or corporate bonds, that's good for the economy since it drives down interest rates which in turn increases investment.
A third way to look at it is: What happens when Americans buy goods from China? The USD have to be exchanged for Chinese RMB, which drives down the value for USD and drives up the value for RMB. This, in turn, makes Chinese goods more expensive in terms of USD and American goods cheaper in terms of RMB. This will either lead to trade being balanced by the Chinese buying additional US goods OR this disparity in currency value will be fixed by the Chinese investing that money in dollar-denominated assets.
Basically, this all leads back to the balance of payments always having to equal zero. The two components of balance of payments, the current account (which measures income earned overseas) and the capital account (which measures the change in ownership of assets) can be in deficit or surplus, but if one is running a deficit than that is perfectly offset by the other running a surplus.
The situation that the US has with China and the rest of the world is quite simple, really: foreigners are buying up US assets, which increases the value of the dollar, which decreases the price of foreign goods when denominated in USD, which causes Americans to buy more goods from overseas. It's that simple, really. So, basically, the trade-off is either you get to produce a lot and sell to the rest of the world OR you get to have a lot of money invested in your economy but then you must run a current account deficit.
Unsurprisingly, studies have backed this up... For example, South Korea was running MASSIVE current account and trade deficits when it was growing quickly. Why? Because there were many investment opportunities in South Korea, so foreigners were pouring their money into that country, which was increasing the value of their currency, so they naturally bought more goods from overseas.
That is precisely what is happening with the US: increased investment opportunities in the US leads foreign investors to invest more in the US, which increases the value of the dollar, which leads to a trade deficit.
HOWEVER, China goes even further than this, or at least used to. They have a policy where their government buys tons of our federal government's debt, in order to devalue their currency, which in turn makes their goods cheaper in terms of the dollar, which leads to Americans buying more Chinese goods from overseas. Of course, politically connected domestic firms and labor unions complain about this and call it "unfair," but the reality is that the Chinese government is helping our economy by funding our large government deficits and thereby keeping interest rates low in the United States.
So... a long post, but it's a subject that doesn't lend itself to simple explanations.
