Why did China actively help Tymoshenko with her disease of COVID-19?

I broadly agree with JMS's answer. There is another element though which I think is missed:

Xi Jinping really really likes TCM:

• Hospitals are now forced to prescribe it. Typically if you go to a public hospital in China, you will receive two prescriptions - one (cheap) for the normal medicine that every other country on the planet uses, and another (hugely expensive) that contains often dozens of mixed herbs. The hospital administrators love it because it provides a sorely needed extra source of funds.

• It could shortly become illegal to criticize TCM in Beijing

This is despite the sad fact that TCM is now one of the leading causes of liver disease in China.

The C.C.P. are doing everything they can to promote its use, both within China and (not very successfully) overseas.

Question:
Why did China actively help Tymoshenko with her disease of COVID-19?

Short Answer:

Because Beijing fears a global backlash over their mishandling of the Virus they have used heavy handed propaganda in a shameless attempt to change the narrative. Extorting positive affirmations from political leaders desperate for assistance has been their goto. This appears to be another example of that behavior, reported by CGTN, a state controlled propaganda institution of the Chinese Communist party.

Traditional Chinese Medicine as a cure to Covid19, Indeed!

Internal Chinese(CCP) report warns Beijing faces Tiananmen-like global backlash over virus
"The report presented early last month (March/2020) by the Ministry of State Security to top Beijing leaders including President Xi Jinping, concluded that global anti-China sentiment is at it's highest since the 1989 Tiananmen Square crackdown."

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Detailed Answer:

This appears to be yet another example of one of the most disturbing behaviors China's Communist Party has exhibited during the Covid outbreak. Targeting political leaders and extorting positive press from those desperate for assistance. If one is afraid and potentially dieing, and one's neighbor comes over with chicken noodle soup, taking a few dozen selfies and demanding you record a video thanking him. Thanking him for soup you typically paid him for. That's not behavior most people would consider acceptable.

• Beijing Demanded Praise in Exchange for Medical Supplies

• China’s ‘Donation Diplomacy’ Raises Tensions With U.S.

• China's medical diplomacy is empowering euroskeptic leaders

• Beijing’s Propaganda Is Finding Few Takers
  "As the Chinese Communist Party embarks on a presumptive goodwill campaign, few in the developing world are falling for it."

• China’s Coronavirus Diplomacy Has Finally Pushed Europe Too Far

With a series of high-level summits culminating in a visit to Germany in the fall by President Xi Jinping, this was supposed to be the year of Europe-China diplomacy. Instead, Europeans are warning of a damaging rift.
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Diplomats talk of mounting anger over China’s behavior during the coronavirus pandemic including claims of price gouging by Chinese suppliers of medical equipment and a blindness to how its actions are perceived. The upshot is that Beijing’s handling of the crisis has eroded trust just when it had a chance to demonstrate global leadership.

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"Often, Chinese officials tell counterparts abroad that they must publicly thank China in return for the shipments."

Take a public phone call between the Presidents of Poland and China, the report is Poland's president was under durres.

Global Backlash Builds Against China over Coronavirus
"Poland wasn't going to get this stuff unless the phone call was made, so they could use that phone call" for propaganda, Ms. Mosbacher US Ambassador to Poland.

Extorting Political leaders for Coronavirus supplies, has been used by China to gain public thanks for the transfers as well as praise for how China's has handled the Coronavirus response.

Germany says China sought to encourage positive COVID-19 comments "Chinese diplomats approached German government officials in an attempt to encourage them to make positive statements on how Beijing is handling the coronavirus pandemic".

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Chinese government asks Wisconsin Senate for a commendation
Senate President Roth strikes back with a China-COVID resolution of his own

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China is not the hero of the Pandemic
You can criticize Trump without parroting Beijing's propaganda