Import subtitles from spreadsheet into Aegisub?
I Couldn't find a way to import into Aegisub, but If the subtitles are in a standard spreadsheet such as Excel, I saved as other format and chose Tab delimited text. Copy all the data in this text file and paste into Subtitle Edit. Then adjust limits on times (Will not overlap the next start time). Then save in whatever format you'd like to use in Aegisub.

I suggest you to use Subtitle Edit because of it's VERY simple sync feature with the video as well as these other abilities. At least it works and you can use Aegisub for your more familiar uses.