1. Based on Billy Kerr's comment, and the link, this is a bug in Inkscape IMHO.

2. The CSS name seems to be coming from the OS/2 tab. If you edit the font (I used fontforge), and change the following, the name goes away. Under Element -> Font Info, in OS/2, there is a drop down for weight class. The name Inkscape gives is slightly different, but I believe this is the source of the CSS name. It's likely recorded as a number, and Inkscape assigns it's own name.

I've partially fixed the problem by:

• Change the weight under OS/2 to an even multiple of 100, whatever is closest.
• Under PS Names, change the Fontname, Family Name, and Name for Humans to something else. I really just added a prefix after Lato. Remember that Fontname can't have spaces.
• Under TTF names, I changed the Preferred Family to the same thing.

Generated the font, deleted old font, and installed new font. Restarted Inkscape and it seems to work.

1. Based on Billy Kerr's comment, and the link, this is a bug in Inkscape IMHO.

2. The CSS name seems to be coming from the OS/2 tab. If you edit the font (I used fontforge), and change the following, the name goes away. Under Element -> Font Info, in OS/2, there is a drop down for weight class. The name Inkscape gives is slightly different, but I believe this is the source of the CSS name. It's likely recorded as a number, and Inkscape assigns it's own name.

I've partially fixed the problem by:

• Change the weight under OS/2 to an even multiple of 100, whatever is closest.
• Under PS Names, change the Fontname, Family Name, and Name for Humans to something else. I really just added a prefix after Lato. Remember that Fontname can't have spaces.
• Under TTF names, I changed the Preferred Family to the same thing.

Generated the font, deleted old font, and installed new font. Restarted Inkscape and it seems to work.

Update: You don't really need to delete the old font. It works fine for other programs. But you will have two of the same if you don't.