Well, this is how the board actually looks like. All of the 100 boards have exact same styling:
https://et.m.wikipedia.org/wiki/Fail:100_lugu_matkateelt_-_Kautla.jpg

The 100 lugu matkateelt is the class of the boards in this case. There are 100 boards with short texts of historical importance. Its not just a title of the board, nor its just one board with such title, its a class or collection of board texts. Basically like a book's main title and then you have titles of each chapter. Of course you can say that the book has a title and each chapter has not title but a book subtitle, but at the same time you can say that the book has a name and each chapter within the book has a title, not subtitle of the book.

Looking at the OSM wiki about name=*:
https://wiki.openstreetmap.org/wiki/Key:name

"As a rule of thumb, the primary name would be the most obvious name of the feature, the one that end users expect data consumers to expose in a label or other interface element."

In this case the "100 lugu matkateelt" is the most prominent name of these boards. As I said, its not just some board or street sign, its the class of boards in this case. Like a book title. 
Since its not just one board but 100 boards, its good to have them not as separate entities but as one collection of boards with board:title=* as each board text titles.

Then again, lets take a book example. Book title is the book name. What is the difference between title and name in this case? Same thing with this type of boards. You have a board name and you have a board title, which one is the name and which one is the title? Remember, they are not separate entities right now, the 100 stories are one single entity, like a book with its stories.

Another perspective: Looking at the map and seeing "100 stories from hiking trail" is pretty much more striking and gives a way to curiosity rather than just seeing "1941 - Kautla lahing". The first gives a way to explore more what it exactly is as far as to find the full collection of the stories, the latter is just a point in time with a board and giving quite zero information besides a fact that there was such battle and most likely the viewer wont even get to know that there are 99 more stories. Even more so, it could be mistaken for just a point where exactly the battle happened. Hence "the most prominent name" aka "100 lugu matkateelt" for name=* tag and board:title="1941 - Kautla lahing" for the title of the text that is inscribed on the board.

Tsitating: "Generally, an information board describes some subject that exists independent of the board. The fact that a board carries a name of a nearby object (or some other text) does not necessarily make this name also into a name of a board."

By this definition the 1941 - Kautla lahing is not in the name and is in the board:title, so basically JOKK?

Then again, you probably could bind them together using relation, naming that relation "100 lugu matkateelt" and then give each board the relation and board:title="1941 - Kautja lahing". This would essentially create third way how to mark them.

The fourth way could be name="100 lugu matkateelt", board:title="54", board:subtitle="1941 - Kautja lahing". Could not find board:subtitle=* tag but I guess there is something that can substitute it.

I propose here to use "100 lugu matkateelt" for a name and "1941 - Kautja lahing" for a board:title. Alternatively we could ask for help for third view on this marking problem.

