" It the cost too outrageous to have the doors changed into french doors? "

Yes, very much so, most likely cost more than the new glass doors would. You would need to disassemble the doors completely. I would not change out either for a frosted glass door. Neither location are a place for a statement door in my opinion.

I don't really get the point of changing those to french doors. A glass butler's door is also very anachronistic. But I agree with others that it will likely be more expensive to adapt these existing doors to french doors rather than just buying good quality wood doors.

I bought Belldinni interior doors with the expectation of being able to find someone to install them. Wrong! There were plenty of sellers and installers of exterior doors but NOBODY wanted to work with interior doors. Finally my brother in law helped me, or rather I helped him. Unless the existing doors are entirely unsatisfactory here's my advice: leave them alone.

I would not change either of those doors. I dont see any reason to want glass in either of them. They look good, just the way they are. I sure wouldnt want guests, to be looking into my pantry.

The reasoning behind changing those door to french ones is because the kitchen is somewhat dark. Hardly any light comes into the room. On the other side of those doors are rooms (Laundry rm and Dining rm) with southern facing windows that get sunlight all day long.
Both rms have tons of light with 3 large windows in each room.
Also, the butler door can be scary coming through when people are around, because you never know when someone is coming from the opposite direction. Bang!!

Also the laundry pocket door will be frosted, so no view just light.

Ruining original doors with glass will not fix the architectural and siting errors that the home suffers from. If the room is dark, add more lighting.