If in previous centuries (before the end of the 12th century) historical events on the territory of modern Ukraine were relatively loosely associated with the history of Poland, then for 13 and there more than 14 centuries the situation has changed. There were more and more episodes, which were covered both from Krakow and from Moscow.
In such situations, the compiler could not simply alternate between the West and the East, but had to somehow coordinate them. And the author of the GL tried to solve these problems, which (with more or less success) continue to solve modern historians.
In this business, he had both successes and failures. Consider first successes (13 episodes).
And now let’s look at failures (8 episodes).
In addition to failures with the synthesis of sources, the author of GL made a lot of mistakes. Some of them migrated to GL from sources in good faith to them, and some belong to the author GL, is a consequence of unsuccessful "improvements" (only 14 episodes).
Thus, we counted 13 episodes, where the author GL successfully combined various sources available to him (and some of these combinations are accepted in modern science). In 8 episodes, attempts at combinations were unsuccessful, as early as 14, there were factual errors – both in a good faith in the sources, and because of unsuccessful attempts to "improve" them.
From the point of view of the contribution to Ukrainian historiography, the work of the author GL must be evaluated highly. He was the first on the way of synthesis of sources and did it much more successfully than his predecessors (the same Stryjkowski). Contribution to science is determined by the fact that our author gave a new one in comparison with what was known in his time (not compared to the modern level of knowledge), and here the author GL has undeniable merits.
But this chronicle does not have a source value, because all its news is taken from sources known to us.