I started by spell-checking each column on a letter by letter basis: the As, the Bs, the Cs... It really demanded added concentration because I had to check each column, row by row. And the content of each column is very distinct from the another: English word followed by the corresponding Portuguese sound followed by the meaning(s) in Portuguese.
At the end of the letter E, I decided to change my strategy, hoping to simplify it. First I copy-pasted all the English words into a separate Excel sheet and did a spell-check... Done! Any editing was also inserted in the master sheet.