SAT writing question

<ol>
<li>Hardly a stranger to self-censorship, Mark Twain never hesitated to change his prose if he believed that the alterations will improve the sales of his books.</li>
</ol>

<p>Is this sentence wrong because you cannot have will/would in an if-clause. Also, should it not be HAD BELIEVED, because he believed first then made alterations or whatever.</p>

<ol>
<li>Some critics have argued that John was unique among 19th century authors in that he surrendered full to his characters and has allowed himself to write in voices other than his own. </li>
</ol>

<p>Do you fix this sentence by changing HAS to just allowed. ***Also because the sentence is in present perfect tense, why aren't any of the other tense verbs in the present tense. Is it because he is dead?</p>

<p>Thanksssss so much you guys.</p>

<h1>1 alterations WOULD improve</h1>

<h1>2 surrendered FULLY</h1>

<p>I would delete the has as you suggested as well.</p>