Clever theme, but I almost missed it. A clue would have been helpful, and easy. In the lowest right hand corner YET could have been MSS. The clue could have been "Manuscripts, and a clue to the theme." [MASS, MESS, MOSS, MUSS]. EGO would be changed to ONS, and BRO would be changed to DRE [as in the rapper Dr. Dre]. See below.
O D O M
U R N S
T E S S
I liked "Whopper of a meal"
for FEAST. [don't normally consider McDonald's a feast]
As for "Enero or mayo" cluing MES, I don't know why Spanish for month
is fair game when other Spanish and other foreign words are not. What makes MES a word anyone but those who know Spanish would know? I suppose it would be a fair argument that the words across are easy enough.