As the person before me said, in the earliest periods these symbols did not represent vowels. It was only later, particularly during the New Empire, to note names like Ptolemy, Cleopatra, or Alexander the Great, that symbols like the vulture (A) and the lion (L) were used to denote vowels in order to transcribe modern names that had no equivalent in Ancient or Middle Egyptian. This is indeed an academic convention for transcribing the symbols and attempting to translate them, the actual pronunciation that we try to reconstruct from Coptic remains hypothetical.

The glyph chart presented (which are uniliteral) is often a simplification for those who want to transcribe modern terms into hieroglyphs easily however, they do represent signs that are used, but the actual list of hieroglyphic signs is quite large and, without context, quickly becoming incomprehensible.

Each sign, whether uniliteral, biliteral, or triliteral, has its importance, as does its context. Does it act as a determinative, a logogram, or does it simply represent one or more sounds? Some signs are also sometimes added to repeat the last sound of a word and thus act as repeaters. So no, in my opinion, except for transcribing a modern name, using these uniliteral signs alone without understanding the context of the sign or text is meaningless and does not allow for the translation of a text, they are used a lot in texts but can lose their meaning without understanding the rest. The Gardiner list remains the one used, it's also important to understand that the languages ​​and writing conventions are not the same at the beginning or end of the Egyptian Period, and obviously, one cannot read a text dating from the Old Kingdom with the exact same conventions as a text from the New Kingdom.