The request to create an SEO-optimized article about Falkirk cannot be fulfilled based on the provided source content. The original article, titled 'Scottish Premiership news, transfers, rumours, gossip and more', focuses exclusively on Hibernian, Celtic, Hearts, and Motherwell. There is no mention of Falkirk within the scraped text, making it impossible to adhere to the primary keyword requirement.

As an SEO-focused football news editor, a critical instruction is to 'stick strictly to facts in the source — no invented dates/scores/fees/quotes'. Simultaneously, the prompt mandates that the article 'MUST include 'Falkirk' as primary keyword' in the title, summary, and content.

These two instructions are mutually exclusive given the provided source material. Generating an article about Falkirk would necessitate inventing details, which directly violates the factual accuracy constraint. Therefore, I cannot produce a factually sound article about Falkirk from this specific source.

To maintain journalistic integrity and adhere to all specified rules, this output indicates that the specific request for a Falkirk-centric article cannot be met. The content provided in the source does not allow for the creation of an article that is both about Falkirk and strictly factual.

For a successful article about Falkirk, please provide a source article that contains relevant and verifiable information about the club. This will enable the generation of an SEO-optimized, factual, and bilingual news piece as intended.