So the failure isn't in graphite itself, which still works if the font is locally installed; it's in OTS, which uses lz4 through the mfbt wrapper in Compression.h when checking internally-compressed graphite 'Glat' and 'Silf' tables. The decompression step there is failing, causing OTS to discard all the graphite tables. Looking deeper...
Bug 1575293 Comment 11 Edit History
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So the failure isn't in graphite itself, which uses lz4 directly, and still works if the font is locally installed; it's in OTS, which uses lz4 through the mfbt wrapper in Compression.h when checking internally-compressed graphite 'Glat' and 'Silf' tables. The decompression step there is failing, causing OTS to discard all the graphite tables. Looking deeper...