Once a 2.0 file has been adjusted to 2.2 (or 2.3) there will be objects that will not work if you try to reopen directly the .lyx in an older version. Unfortunately due to web limitations your sample was truncated and I had to adjust the file manually to get it to load in 2.3 without problems other than it wanted to load as Swedish!

It is normal for an applications new version to read an old version file and make adjustments to new format. However "back-porting" is notoriously difficult. In such case the "new" version would best be exported to a different type and then imported to "old" version.
Catch22 you do not have a working new application to back-port, so either
A) need a different build / continue to try to UpRev application
B) Handover file to someone who can back-port/convert to version 2.0 or export in a suitable format for 2.0 however I could not guarantee it would be 100% successful in formatting.
My tests with your initial MWE which was tagged as 2.2 converts reasonably well in 2.0.1 but I do not know if parts are missing try this and compare
#LyX 2.0.1 created this file. For more info see http://www.lyx.org/
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PLAYING IT BY EAR
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Cheryl Rao
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2018
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Playing It By Ear
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(c)
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2018 Cheryl Rao
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Published in 2018 by
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Goa,1556, Sonarbhat, Saligao 403511 Goa, India.
http://goa1556.goa-india.org, [email protected] +91-832-2409490
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in association with
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The Margao (Rua Abade Faria) bookshop with a difference
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10 9 8 7 6 5 4 3 2 1
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Typeset with \SpecialChar
, http://www.lyx.org.
Text: Bitstream Charter, 9.8/14.
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See Goa,1556's catalogue at: http://goa1556.in
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PROLOGUE: Building up to the big day
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sat quietly in the corner of the cement bench of the
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The Croft
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She knew she couldn't be seen from inside the house, even if Mai or Papa
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She had drawn herself up into as small a bundle as possible, her bare feet
on the bench, her arms wrapped around her knees and her head resting on
her arms.
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The End
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