InDesign translation issue

Hopefully you used Styles - you can change the language in the style which is the best option. 

Typically I create 1 style for the Body Text - then Base all styles off this, so when it comes to making global changes I just have to change the Body Text. 

Body Text - Parent 

Bullets - child (Based on Body Text)

Indented text - child (Based on Body Text)

Numbered text - child Based on Body Text)

and any other body text

Header - (Based on Body Text) - change in size, font style etc. 

Sub Heading - this would be a child of Header - (Based on Header) - change in size etc

Then to change the Language - you would only have to change the Body text  - and it cascades to the the rest of the styles (as you wouldn't change the language in any of them - so they all relate back to the Body Text style)

This looks complicated - but it's not - and it's really easy to reprogram your styles to behave like this. 

For each style - except Body text - edit the style - 

For example - edit Bullets then remember your bullet settings, set the Based On to Body text - then Reset your Style to the Base - then input your Bullet settings again.

For Sub bullets - set the Base Style to Bullets - reset to base - reinput the Sub Bullet value/style (dot/dash etc).

It will only take a few moments to get everything back to being related to the Body Text style. 

This gives you greater control over global changes in your document.

Body Text
   ├── Bullets (based on Body)
   │      ├── Sub Bullets (based on Bullets)
   │      ├── Sub Sub Bullets (based on Sub Bullets)
   │            └── Etc.
   │
   ├── Numbered (based on Body)
   │      ├── Sub Numbering (based on Numbered)
   │      ├── Sub Sub Numbering (based on Sub Numbering)
   │            └── Etc.
   │
   ├── Indented (based on Body)
   │      ├── Sub Indented (based on Indented)
   │      ├── Sub Sub Indented (based on Sub Indented)
   │            └── Etc.
   │
   ├── Header (based on Body)
          ├── Subheader (based on Header)
          ├── Sub Subheader (based on Subheader)
                └── Etc.
etc.

The other suggestions have been great - and I use similar to @Laubender in the past when in a pinch. 

You can use this script that I attach to my answer. I am not the author and I don't remember where it comes from. The 2 things I know are that:

1.  it works perfectly
2. It has been developed by a German speaking person (interface is in German).

https://www.dropbox.com/scl/fi/l525uhm1fqvcuzrih2n3s/changeLanguageOfStyles_xl.jsx?rlkey=deufrx63vz2ifmac4hgrgr5du&dl=0

Edit: I just saw that the post is 2 and half years old!

You may not have to try so hard.. LangoAI Translator for InDesign, an AI-powered translation workflow plug-in available on Adobe Exchange. I’d love to share what it does at a high level and get feedback from people who translate/catalog/layout in multiple languages... 

https://exchange.adobe.com/apps/cc/255b78e1/langoai-translator-for-indesign

Text frames (you call them boxes) have nothing to do woth language. Language is a character property and you find its settings in Paragraph and Character Styles. You should change the language in Paragraph styles. Character Styles are for overrides.

If you build up your paragraph style base on one root style you need only to change the language in that style, all other—based on this style or based od children of this style—inherit the language. When you change the one style, all other will change too.

@Laubender is right, inasmuch as the language attribute is a text attribute, not a text-frame attribute.

So when you say that you change the "textboxes to English," that doesn't really make sense.

You'd need to select all the text and change it's language to English.

Uwe suggests one way of doing that, with find/change.

The disadvantage is that you'll have a lot of paragraph and character overrides.

Another suggestion would be to create an English template that has all the same paragraph and character styles (i.e., the same names in the same groups), and then "Load all text styles" from that English template when you've finished translating.

If you did this first and then finish off with Uwe's suggestion, you'd get the least number of overrides.

Hi @Carsten Lynge27992355e60i ,

usually that is done by changing the language of the applied paragraph styles.

However, there could be a lot of overrides on a character by character basis.

You could do this with a GREP Find/Change action after you changed all paragraph styles in the document.

Search pattern is:

.+

Change to English.

Scope: Document

Regards,
Uwe Laubender
( Adobe Community Expert )