The following input breaks when translated using cxserver:
Produced on https://dev.translatewiki.net/w/i.php?title=Special:ContentTranslation&page=Vantaa&from=en&to=es&targettitle=Vantaa&version=2 (first section after infobox).
```
<section id="cxTargetSection1" data-mw-cx-source="undefined"><p id="mwBQ"><span data-segmentid="218" class="cx-segment"><b id="mwBg">Vantaa</b> (<small about="#mwt7" data-mw="{"parts":[{"template":{"target":{"wt":"IPA-fi","href":"./Template:IPA-fi"},"params":{"1":{"wt":"ˈʋɑntɑː"}},"i":0}}]}" id="mwBw" typeof="mw:Transclusion" data-ve-no-generated-contents="true">Finnish pronunciation:<span typeof="mw:Entity"> </span></small><span about="#mwt7" class="IPA" id="mwCA" title="Representation in the International Phonetic Alphabet (IPA)" data-ve-ignore="true"><a class="cx-link" data-linkid="219" href="./Help:IPA/Estonian_and_Finnish" rel="mw:WikiLink" title="Help:IPA/Estonian and Finnish">[ˈʋɑntɑː]</a></span>; <a about="#mwt8" class="cx-link" data-linkid="220" data-mw="{"parts":[{"template":{"target":{"wt":"lang-sv","href":"./Template:Lang-sv"},"params":{"1":{"wt":"Vanda"}},"i":0}}]}" href="./Swedish_language" id="mwCQ" rel="mw:WikiLink" title="Swedish language" typeof="mw:Transclusion" data-ve-no-generated-contents="true">Swedish</a><span about="#mwt8" data-ve-ignore="true">: </span><i about="#mwt8" lang="sv" data-ve-ignore="true">Vanda</i><link about="#mwt8" href="./Category:Articles_containing_Swedish-language_text" id="mwCg" rel="mw:PageProp/Category" data-ve-ignore="true">) is a city and <a href="./Municipalities_of_Finland" rel="mw:WikiLink" data-linkid="221" class="cx-link" id="mwCw" title="Municipalities of Finland">municipality</a> in <a href="./Finland" rel="mw:WikiLink" data-linkid="222" class="cx-link" id="mwDA" title="Finland">Finland</a>. </span><span data-segmentid="223" class="cx-segment">It is part of the inner core of the <a href="./Greater_Helsinki" rel="mw:WikiLink" data-linkid="224" class="cx-link" id="mwDQ" title="Greater Helsinki">Finnish Capital Region</a> along with <a href="./Helsinki" rel="mw:WikiLink" data-linkid="225" class="cx-link" id="mwDg" title="Helsinki">Helsinki</a>, <a href="./Espoo" rel="mw:WikiLink" data-linkid="226" class="cx-link" id="mwDw" title="Espoo">Espoo</a>, and <a href="./Kauniainen" rel="mw:WikiLink" data-linkid="227" class="cx-link" id="mwEA" title="Kauniainen">Kauniainen</a>. </span><span data-segmentid="228" class="cx-segment">With a population of <span about="#mwt181" data-mw="{"parts":[{"template":{"target":{"wt":"formatnum: {{Infobox Finnish Municipality/population count|Vantaa}}","function":"formatnum"},"params":{},"i":0}}]}" id="mwEQ" typeof="mw:Transclusion" data-ve-no-generated-contents="true">221,821</span> (<span about="#mwt10" data-mw="{"parts":[{"template":{"target":{"wt":"#time: j F Y","function":"time"},"params":{"1":{"wt":"{{Infobox Finnish Municipality/population count|sourcedate}}"}},"i":0}}]}" id="mwEg" typeof="mw:Transclusion" data-ve-no-generated-contents="true">31 August 2017</span><sup typeof="mw:Extension/ref" data-ve-ignore="true" data-mw="{"name":"ref","attrs":{"name":"population_count"},"body":{"html":""}}" class="mw-ref" about="#mwt12" id="cite_ref-population_count_3-1" rel="dc:references"><a href="./Vantaa#cite_note-population_count-3" style="counter-reset: mw-Ref 1;"><span class="mw-reflink-text">[1]</span></a></sup>), Vantaa is the fourth most populated city of Finland.</span></p>
</section>
```
As a side effect, this causes
```
jQuery.Deferred exception: model.getSectionNumber is not a function TypeError: model.getSectionNumber is not a function
at VeInitMwCXTarget.<anonymous> (https://dev.translatewiki.net/w/extensions/ContentTranslation/modules/ve-cx/init/ve.init.mw.CXTarget.js?3496c:678:46)
at fire (https://dev.translatewiki.net/w/resources/lib/jquery/jquery.js?6a07d:3268:31)
at Object.fireWith [as rejectWith] (https://dev.translatewiki.net/w/resources/lib/jquery/jquery.js?6a07d:3398:7)
at process (https://dev.translatewiki.net/w/resources/lib/jquery/jquery.js?6a07d:3622:22)
at Object.<anonymous> (https://dev.translatewiki.net/w/resources/lib/jquery/jquery.js?6a07d:3632:9)
at mightThrow (https://dev.translatewiki.net/w/resources/lib/jquery/jquery.js?6a07d:3534:29)
at process (https://dev.translatewiki.net/w/resources/lib/jquery/jquery.js?6a07d:3602:12) undefined
```
This is because model is `VeDmCXPlaceholderNode` and it is that because translation failed, tries to fallback to the source text, but that one fails too, and placeholder is not replaced with new content.