Hi @Jdforrester (WMF),
Thank you for your response. I've checked carefully and TemplateStyles is installed on my Wiki. I have the following information in Special:Version:
TemplateStyles 1.0 (e5da5c0) 18:14, 18 April 2018
In my LocalSettings.php file, these extensions are loaded in this order (note that the list is not fully displayed):
Cite
ParserFunctions
WikiEditor
VisualEditor
Scribunto
TemplateData
TemplateStyles
Citoid
I really don't understand why these tags appear. I obtain the same kind of error than if I remove the load of the extension.
Notice that in Module:Citation/CS1 page that I've imported from Wikipedia, multiple tags appear (thus, they are not parsed correctly). For example:
<section begin=header /> and <section end=header />
<section begin=module_components_table /> and <section end=module_components_table />
And so on. Maybe this issue is related with the one that I have with the tags of TemplateStyles?
Do you know what is the root of such problem(s)? I'm trying to find any relevant documentation on that, but I found nothing until now.