Incorrect conversion to HTML

[RobKolanko]

The following is an example of Textile text that does not format correctly to HTML using the textile specs.
This Text:

(iii) Txt1.
(5) _Italic._ (i)(_a_) txt2.
(_b_) txt3.
(ii) txt4

Using redcloth output looks like the following with the italics.
(iii) Txt1.
(5) Italic. (i)(a_) txt2.
(_b) txt3.
(ii) txt

I believe the HTML conversion is incorrect

<p>(iii) Txt1.<br/>
(5) <em>Italic.</em> (i)(<em>a_) txt2.<br/>
(_b</em>) txt3.<br/>
(ii) txt</p>

Where this example should look like the following with the italics as per https://txstyle.org/
(iii) Txt1.
(5) Italic. (i)(a) txt2.
(b) txt3.
(ii) txt4

correct HTML?

<p>(iii) Txt1.<br />
(5) <em>Italic.</em> (i)(<em>a</em>) txt2.<br />
(<em>b</em>) txt3.<br />
(ii) txt4</p>