The Tibetan spacing combining marks U+0F3E, U+0F3F, and U+0F7F are not spacing in this font, because they are mark glyphs. They should be base glyphs, or a 'dist' lookup should add width for them.
Character data
༠༾༶༠༿༶ཧཿ༶
U+0F20 TIBETAN DIGIT ZERO
U+0F3E TIBETAN SIGN YAR TSHES
U+0F36 TIBETAN MARK CARET -DZUD RTAGS BZHI MIG CAN
U+0F20 TIBETAN DIGIT ZERO
U+0F3F TIBETAN SIGN MAR TSHES
U+0F36 TIBETAN MARK CARET -DZUD RTAGS BZHI MIG CAN
U+0F67 TIBETAN LETTER HA
U+0F7F TIBETAN SIGN RNAM BCAD
U+0F36 TIBETAN MARK CARET -DZUD RTAGS BZHI MIG CAN
Font
NotoSerifTibetan-Regular.otf
Where the font came from, and when
Site: https://github.com/googlei18n/noto-fonts/blob/b20c9c07139b22eb38013b1f80f9a5222c6058c6/phaseIII_only/unhinted/otf/NotoSerifTibetan/NotoSerifTibetan-Regular.otf Date: 2018-10-12
Font version
Version 2.000
Issue
The Tibetan spacing combining marks U+0F3E, U+0F3F, and U+0F7F are not spacing in this font, because they are mark glyphs. They should be base glyphs, or a 'dist' lookup should add width for them.
Character data
༠༾༶༠༿༶ཧཿ༶ U+0F20 TIBETAN DIGIT ZERO U+0F3E TIBETAN SIGN YAR TSHES U+0F36 TIBETAN MARK CARET -DZUD RTAGS BZHI MIG CAN U+0F20 TIBETAN DIGIT ZERO U+0F3F TIBETAN SIGN MAR TSHES U+0F36 TIBETAN MARK CARET -DZUD RTAGS BZHI MIG CAN U+0F67 TIBETAN LETTER HA U+0F7F TIBETAN SIGN RNAM BCAD U+0F36 TIBETAN MARK CARET -DZUD RTAGS BZHI MIG CAN
Screenshot