@aFFi ... hahaha, nope.
About two thirds of the current Demon Lords are powerful enough to easily beat Rimuru.
The only ones out of the 10 current demon lords who would have a difficult fight against Rimuru at this point in the story are Carillon/Carrion(depending on the translation)(he's the beastman one), Frey(the harpy-like one), Clayman(the manipulating one) and Ramiris.
However, Ramiris is a special case. Her powers in her Labyrinth(which she can summon anywhere and shape in any way she wants) are INSANELY powerful. It's just that they aren't combat-focused abilities. Also, she currently has special circumstances and is in a weakened form. In her past form her power was comparable to that of Milim and Veldora.
Then, as for all of the 6 other current Demon Lords, they are all insanely powerful, though they are also all eccentrics who just do their own thing.