ظَهَرَ نَجْمٌ بَيْنَ السُّحُبِ.
A star appeared between the clouds.
إِنَّ نَجْمًا قَدْ ظَهَرَ بَيْنَ السُّحُبِ.
Indeed, a star did appear between the clouds.
An uncommitted listener may need only the unmarked statement. Someone who assumes the entire sky remained obscured may warrant the reinforced assertion with inna and qad.
Rhetorical emphasis does not replace evidence. Excessive confidence can be inappropriate when the observer is themselves unsure of what they saw.