Characters in FontForge appear distorted

Question

I'm trying to create a font using FontForge which is 'simply' the alphanumeric characters from Lato (original version) as well as the greek alphabet characters from Lato (extended version). I opened both fonts in FontForge and copied and pasted the greek letters over to the original version. I generated the font and displayed it in Google Chrome. But the characters that I've copied come out jagged / distorted. I've also tried opening the original font, then going to element and then merge fonts and selecting the extended version font and then generating a font from that but the same problem occurs.

The screenshot provided below shows the distortion going on. The top line shows how the letters should look. The bottom line shows how the letters actually look. Many of the letters - even the ones that were in the original (such as the 'a') - aren't displaying properly. The bottom and top of some characters has been flattened and for other characters, extended. Notice the top of the alpha, rho and epsilon are pointed and aren't smooth as they should be. The top of the beta has been flattened. Look at the top and bottom of the 'o' - both have been flattened as if to fit into a minimum allowable area.

If I zoom in a lot, the jagged edges become smooth again.

What can I do to fix this?