To me it's clear that traits of character and tendencies are one and the same thing.

A noble character is earned by individual effort through the merits and grace of Christ. ... Conflict after conflict must be waged against hereditary tendencies. We shall have to criticize ourselves closely, and allow not one unfavorable trait to remain uncorrected. {AG 112.4}

"And I, if I be lifted up from the earth, will draw all men unto me." The question is asked, Why then are all not drawn to Christ?--It is because they will not come; because they do not choose to die to self; because they wish, as did Judas, to retain their own individuality, their own natural and cultivated traits of character. Altho they are given every opportunity, every privilege, yet they will not give up those tendencies which, if not cut away from the character, will separate them from Christ. If, continuing to cherish these traits of character, they were admitted to heaven, they would cause a second rebellion. {ST, July 8, 1897 par. 7}

Each soul inherits certain un-Christlike traits of character. It is the grand and noble work of a lifetime to keep under control these tendencies to wrong. {HP 231.2}

Also, I don't see a difference, in practical terms, between inherited and cultivated tendencies of character.

Thank you for clearly expressing your belief. As you know, I believe inherited and cultivated tendencies (inclinations, propensities) and inherited and cultivated traits of character are separate but related aspects of human nature.

I have a vague remembrance that you believe that. What do you say is the difference between tendencies and traits?

A trait is a quality of character; whereas, a tendency is a propensity, inclination. Tendencies drive, propel, force people to develop, cultivate specific traits of character. Repetition of thoughts, feelings, words, and behavior results in character that counts in judgment.

Let's analyze an example. EGW says:

The great hereditary and cultivated tendency to evil with Judas was covetousness. {2MCP 598.3}

The leading traits in the character of Judas were covetousness and self-esteem. {ST, June 5, 1884 par. 3}

What is the difference between covetousness as a tendency and as a trait of character?

If a tendency was something people inherited and trait was something people cultivated, what you said would make sense. But Ellen White speaks indistinctly of hereditary and cultivated traits of character and of hereditary and cultivated tendencies of character, so I don't see how these could be different. There are many quotes that could be cited, but just two will suffice:

Objectionable traits of character, whether hereditary or cultivated, must be compared with the great rule of righteousness, and then conquered in the strength of Christ. {CT 449.1}

So long have they chosen to follow their own way and their own wisdom, so long have they cherished defective hereditary and cultivated tendencies of character, that they are blind and cannot see afar off. {1MCP 38.3}

As I said, traits and tendencies are related but separate aspects of human nature. By the way, both traits and tendencies are inherited and can be cultivated. Developing specific traits of character strengthens and fortifies the corresponding tendencies parents bequeath to their children. Which in turn predisposes them to develop, cultivate the same traits of character. Nevertheless, God will not hold children accountable in judgment for the traits of character their parents cultivated. In judgment each person will be held accountable for the traits they themselves cultivated.