Maybe you'll consider using abbreviations for names of big numbers?
k, M, B, T, Qa, Qi, Sx, Sp, Oc, No, Dc, UnD, DoD, TrD, QaD, etc.

They seem as much understandable as full names. I mean if one doesn't know what quattuordecillion is, he also won't understand QaD, and vice versa. But in the same time abbreviations look nicer =)

Or it could be adjustable in settings, three options for naming:
• full names (billion)
• abbreviations (B)
• powers of 10 (×10^9)

Realistically I don't think players will reach these values. Why change it?

Because of the same reason you implemented it. =)

If I remember correctly, Lua uses int64. It's 18 Qi (or 18×10^18).
Max playthrough length of a Factorio run is int64 ticks. It's 10 billion years.
If a player will start inputting items into mem.unit on 100k/sec and will continue doing it for 100 years, he'll use capacity of 315 T (or 315×10^12) items. It's 58k times less than int64 can be.

So why implemented it? xD

New suggestions:
1. Remove from localization file lines 55-1048 (from 8=__1__ sextillion to 1001=__1__ nongennovemnonagintillion). 1k lines less to localise. And my OCD won't let me skip those unneeded 1k lines. =)
2. The same for logic.
3. Abbreviate names. =)

I think its good as-is. For your localization I recommend to just copy the English translation on lines 55-1048.