Legacy engine provides some data which are not available LSTM, e.g. font
information, so it is not obsolete and a user should be able to use it
regularily. The data for the legacy engine are in different directory,
so there is no conflict. However the current package is configured
to see a conflict here, e.g.

Hi Janusz,

Tesseract 4 uses tesseract-ocr-deu and tesseract-ocr-script-frak.
Tesseract 3 uses tesseract-ocr-deu-frak

I am worried about confusing users. If we include both sets of language
data in Debian, there will a huge number of choices, and some users
might feel overwhelmed. However, Alexander thinks it could work with
careful
package naming, like this:

https://mentors.debian.net/package/tesseract-lang-legacy

I am also a little worried about the support costs of exposing lots of
users
to the legacy engine. It will make it harder to remove the legacy engine
completely from future Tesseract.  Especially if other Debian packages
start to have dependencies on it. Also bug reports against the legacy engine
will not get much attention from upstream.

We'll discuss this with upstream, but in the meantime I have a question for
you: What is your best guess for how many people are like you, and want to
use the  Tesseract 3  engine in Debian?

Thanks,
Jeff

I don't use Tesseract actively at the moment but subscribe to the
tesseract issues. I don't read them carefully but have an impression
that, at least at the very moment, Tesseract 4 traning data are not
necessary better then the legacy ones.

[...]

To say the truth, I'm aware of only one other person. He became confused
by the different paths to training data on Ubuntu and reported his
problem as an issue, which has been closed almost immediately;
unfortunately I'm unable to find quickly the issue numeber.

Best regards

Janusz