Maybe there is a tweak installed that causes problems. I'm running out of other ideas.

Does changing to German do anything?

Are you running the latest iOS version? No jailbreak?

Even with these settings, Textastic shows in English for me:

I have duplicated your settings on my iPhone running iOS 14.6, but I cannot reproduce the issue. I see Textastic localized to English with these language settings.

Which iOS version are you running?

Can you try if tapping "Add Language…" and choosing English (UK) changes anything?

Can you show me a screenshot of Settings -> General -> Language & Region?

The preferred language order should have all languages you know.

This could be for example:

iPhone Language: "English (US)"

Preferred Language Order:

English (US)

German 

Maybe the list of preferred languages is missing English for you?

That's weird - I haven't seen this before.

Can you please have a look at the iOS Settings app and then scroll down to Textastic? You should find a setting to set the language to English there.

Hello,

Textastic 5.3.1, which was released more than 5 years ago, can no longer be launched on iOS 14.5 and later due to changes made by Apple.

The current version 9.6.4 supports the latest features of iOS 14 and is available as a separate app in the App Store: Textastic Code Editor 9. If you install the new app while the old app is still on the device, all your files and remote connections will be migrated to the new app automatically.

Textastic 5.3.1 is no longer sold on the App Store and thus can no longer be updated. However, existing customers can still download the app for older iOS versions.

Textastic 6.0 was released in March 2016 and was the first paid upgrade since version 1.0 was released in 2010.

Hi, how exactly are you currently renaming files in Textastic?

Hello,

please check if you have "Read-Only" enabled in Textastic's settings -> Code Editor -> Keyboard. The text of the option is red if it is enabled.

See https://www.textasticapp.com/v9/manual/customization/settings.html#keyboard

I just tested this in Textastic and in the Mac app "Marked 2", and looked at the HTML source generated by both apps.

Textastic uses the MultiMarkdown library, Marked 2 can switch between the Discount library and MultiMarkdown.

Using Discount in Marked 2, the link is unescaped, so "\." becomes ".". But if I use the MultiMarkdown processor in Marked 2, the same thing happens as in Textastic and "\." stays "\.".

I guess the "/." you are seeing is just Safari/iOS trying to interpret the URL. It is not what's in the the generated HTML source code.

So it looks like MultiMarkdown doesn't support escaped characters in Markdown links. Unfortunately there is not much I can do about this, unless I would switch to another Markdown library.

With both libraries, "&" becomes "&" however - so you should just use "&" instead of "&" in the Markdown file.