Created attachment 122000 [details]
Spell-check work-around and bug--see paragraph 2

Spell check in Calc does not work *at all* (without a special work-around), simply because one cannot set the spell-check language! I marked this item as "critical" because it prevents Calc from being used in a professional environment, where spell-check is a must-have. 

Finding the work-around has taken me about 5 hrs of research time. Most people would give up long before then.

In Writer, I can go to Tools --> Language --> For all text --> English (USA), and spell-check works fine, now that I have selected the language.

In Calc, however, this option does not exist. I cannot set the language at all via the Tools --> Language menu, as the "For all text" submenu is nonexistent. 

Work-around: 
Highlight all cells (ctrl + a) → right click → Format Cells → Font → set “Western Text Font” to the language you want to use for spell-check, ex: “English (USA).” Now that you have set the language, spell-check will work when you click the spell-check button. 

Note: I have the following spell-check dictionaries installed: Arabic, English, Spanish, French, Italian, Portuguese. 

I am running Windows 8.1, so I don't know if this problem is on other OSs too.

I have attached a document ("LibreOffice Tweaks, Help, Tips, Tricks, & Notes - Gabriel - 20160116.pdf") detailing the process in paragraph 2. Note that there is also a second, lesser bug which makes "automatic spell checking" NOT retroactive to already-existing text. See the attachment, under the subparagraph 2.1.2 for more details.