For certain words, both heavy and light forms of ra at a pause are transmitted. The cases «مِصْرَ» and «الْقِطْرِ» illustrate that the earlier vowel can suggest one result while the ra’s own original vowel remains relevant.
«مِصْرَ» — final ra originally has fathah; both treatments are discussed at a pause.
«الْقِطْرِ» — final ra originally has kasrah; both treatments are likewise mentioned.
The source favors looking to the original vowel of ra in these particular instances: heavy for Misr and light for Qitr. Such a narrowly reported variant should not be generalized to every paused ra.