Why are you misleadingly quoting this wall of text as if it supports your thesis when it doesn't?

The fact of the matter is that the KMT by far did most of the fighting against Japan. This was directly admitted by Lü Zhengcao himself. It is also the mainstream view held by war historians. See [0] for a quick summary. You are the one putting forth a revisionist thesis.

The CCP's priorities were clarified in the orders Mao issued to the Eighth Route Army:

The Sino-Japanese war affords our party an excellent opportunity for expansion. Our fixed policy should be 70 percent expansion, 20 percent dealing with the Kuomintang, and 10 percent resisting Japan.

There are three stages in carrying out this fixed policy: the first is a compromising stage, in which sell-sacrifice should be made to show our outward obedience to the Central Government and adherence to the Three Principles of the People [nationality, democracy, and livelihood, as outlined by Dr. Sun Yat-sen], but in reality this will serve as camouflage for the existence and development of our party.

The second is a contending stage, in which two or three years should be spent in laying the foundation of our party’s political and military powers, and developing these until we can match and break the Kuomintang, and eliminate the influence of the litter north of the Yellow River. While waiting for an unusual turn of events, we should give the Japanese invader certain concessions.

The third is an offensive stage, in which our forces should penetrate deeply into Central China, sever the communications of the Central Government troops in various sectors, isolate and disperse them until we are ready for the counteroffensive and wrest the leadership from the hands of the Kuomintang.

From [1]:

By the CCP’s own accounts during the war, it barely played a role. Specifically, in January 1940 Zhou Enlai sent a secret report to Joseph Stalin which said that over a million Chinese had died fighting the Japanese through the summer of 1939. He further admitted that only 3 percent of those were CCP forces. In the same letter, Zhou pledged to continue to support Chiang and recognize “the key position of the Kuomintang in leading the organs of power and the army throughout the country.” In fact, in direct contradiction to Xi’s claims on Wednesday, Zhou acknowledged that Chiang and the KMT “united all the forces of the nation” in resisting Japan’s aggression.

From [5]:

Of course, wariness of fighting Japan was not the only reason Mao preferred guerrilla tactics to mobile warfare. Political calculations were at work as well. By focusing on the construction of base areas behind Japanese lines, Mao knew the CCP could build up its strength and improve its position vis-a‘-vis the KMT. Years later, one of Mao’s secretaries would recall a revealing remark Mao made to Lin Biao after the revolution: “Some comrades believed the less land Japan occupied, the better, only later was there unified recognition: allowing Japan to occupy more territory is the only way to love your country. Otherwise, it would have become a country that loved Chiang Kai-shek.” This comment, made to close associates in confidence, suggests that Mao saw Japan’s invasion as an opportunity to boost the CCP’s position in its continuing struggle with the KMT.

For example, after the Hundred Regiments Offensive [4], Mao purged Peng Dehuai for "wasting resources" fighting the Japanese rather than the KMT.

Even the CCP itself has been (slowly) starting to publicly acknowledge the historical truth [2][3].

[0] https://www.quora.com/Who-deserve-greater-credit-for-driving...?

[1] https://thediplomat.com/2014/09/the-ccp-didnt-fight-imperial...

[2] https://www.scmp.com/article/979073/historians-mainland-give...

[3] https://www.scmp.com/comment/insight-opinion/article/1591802...

[4] https://en.wikipedia.org/wiki/Hundred_Regiments_Offensive

[5] https://www.jstor.org/stable/20192272