Prediction
Values inferred from one set of texts should explain other texts that were not used to construct the proposal. A successful decipherment predicts recurring words, grammatical patterns and historically plausible content. If every failed sign is assigned a new exception, the proposal is not constrained enough to test.
Levels of understanding
A script may have recognizable numerals or repeated names while the language remains unidentified. A language may be known but written in a partially unread script. Some signs can be read securely while others remain disputed. Label these states separately; “deciphered” is not a single switch.
Documenting the reading
The Maya hieroglyphic handbook models an explicit distinction between sign transliteration and linguistic transcription. A teaching tool should expose both and cite the evidence for sign values. A smooth English sentence without the intervening readings is not a demonstration.
Modern-language examples on this page clarify a linguistic pattern. They do not establish unattested sounds or forms for an ancient language. Follow the cited sources below and keep editorial readings separate from the surviving trace.