There was a single typo at about 22:35 in the original subtitle (use = us). You can mux out the old one and add this corrected version if you wish, using "mkvtoolnix (mkvmerge GUI)", a freeware utiliy easily found if you google.
Alternatively, since the subbtitle file is text based, you could just mux it out, open it in notepad (or any other text based editor) and make the change at line 0:22:33.17. Then mux the original back in.
File list
[ByteSize] Plastic Little OVA subtitles revision 2.ass (62.8 KiB)
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